Overly difficult? Too easy? Effective UX frontier
Designers:
We are not our users.
Moreover, we are not experienced users.
I have often seen many candidates forget this important detail during interviews.
We usually show them a complex screen of our B2B finance programs used by financial advisors and investment experts and ask them to explain the design process they recommend to improve the product. Some people say: “Wow, too much information, I insist on a major redesign – I couldn t use a program like this.”
What about understanding the user s context …? I do not expect them to use this program. Unless, of course, one day they become financial experts.
It turns out that we all tend to think that all products are meant exclusively for us. We made a similar mistake on our team (story here), I was wondering why this bias is so common among designers, compared to developers or project managers.
This is because today, due to lack of time, the vast majority UX-Courses and trainings do not give their students difficult tasks related to the fields of health care, education and banking?
Could it be because people prefer shiny Spotify or Deliveroo redesigns for their portfolio?
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Welcome to the world of interfaces for experts and professionals
Behind each major application is an advanced version for power users – for “power users” or company employees. You will not see the extended version unless you are part of this narrow circle.
Take booking systems, for example. Any good booking system today offers a simple step-by-step process … But what about travel agents who book tickets all day?
Business professionals and your employees don t need you to look after them like a child. Their responsibility is to know the principles of their work.
Notice how different the two screens are in the screenshots below. Both images are an application interface for Eurostar, a company that operates the train service between London and Paris. On the left is the most simplified interface for clients. On the right is a more compact behind-the-scenes interface for company employees:

Eurostar employees use this interface all day and should see detailed information on availability, combinations of departure and arrival dates, currency settings, etc. To serve customers effectively, they need to see all of this information on one screen.
Here s another example from Societe Generale CIB, the company I work for:
We offer our clients 2 different interfaces, depending on their needs. One for general users and one for forex professionals. Although both products use the same server systems, they are designed differently.
Why? Because user contexts are very different.
Product 1: SG Markets MyFX

This product is for small and medium-sized CFOs in France. Everything is very simple, and in the process of currency transactions, users receive step-by-step support. The experience is close to what you would expect from personal banking at neobank.
But what about the CFOs of large international companies, foreign exchange specialists and our employees? They will be limited to such a simplified interface. They must simultaneously monitor multiple currencies and work with financial instruments. So instead they use …
Product 2: SG Markets Foreign Exchange

Again, this is a product for forex professionals and employees of our company. This interface is designed to enable them to work efficiently and remain professional.
Unlike large consumer base products, which offer the simplest experience to the largest number of users, products for experts or employees should be tailored to their specific professional use case.
Depending on the audience, the challenge for designers is to find a balance between “not too easy” and “not too difficult.”
So how do we find this middle ground?
Let s call on the UX Efficient Frontier to help!
What is UX Efficient Frontier
Initially, the concept of “Efficient Frontier” was formed on the basis of the financial theory of effective investment management, taking into account risks and profitability.
Having worked for many years in B2B design, I realized that this concept can be adapted to the UX, for designing appropriate products, taking into account the professional experience of people (business expertise) and experience in using interfaces (interface expertise)…
But first, let s clarify the differences.
Professional experience
Professional experience is the knowledge of a person in a particular field or topic, gained through study, business training, or work experience. It also includes mental models of how the user approaches their tasks and processes.
For example, most finance professionals are advanced enough to use Excel and often expect to be able to manipulate data as efficiently as they can in Excel.

Experience in using interfaces
Experience in using interfaces is knowledge about how an interface works, gained through learning it, habits of using it, or experience of using similar interfaces. As the experience increases, so does the user s ability to recognize familiar interaction patterns instead of analyzing or recalling them.

Now, if we add 2 criteria together.

- Any design above the curve is too complicated: you make it difficult to use your service.
- Any design below the curve is oversimplified: you destroy the value of the application to the user and put them at risk of becoming unable to do their job.
- The curve is the “effective border UX“. It represents the middle ground between professional experience and the experience of using your users interfaces.
Let s take a closer look.
Understanding and using the border
Here are some examples to help you understand the curve better:
Example 1: Little Experience with Interfaces with Little Professional Experience

This is what most products with a broad customer base are aimed at. You think about your consumer s needs for food delivery, listening to music, booking a train ticket, and so on, when you are not a grocery manager, music publisher, or travel agent.
Example 2: High level of experience in using interfaces with an average level of professional experience

This is the category that many legacy tools fall into. They were designed with the system in mind, not the users. Professional experience was also assumed to imply experience using interfaces. End result: people are overwhelmed and complain about the complexity of the interface.
This is our bread B2B design teams… We are constantly figuring out how to design the best experience for professional users given the complexity of their business.
Example 3: Poor experience of using the interface with a high level of professional experience

Dangerous zone. The interface is too simplistic. Promising to make work easier and easier (and screens are, of course, “sexier”), we deprived our users of useful features and controls.
In my opinion, this is the biggest problem for designers who find themselves in a complex project with limited user access. There is a high risk that they will eventually design a black box.

As Don Norman said in his book “Life in a Complex World” and speaking at the conference:
Life is hard and the tools have to match life.
This is why the effective UX border is a curve, not a line:
- Throughout life, people progress. You can start implementing advanced interface features such as keyboard shortcuts and keyboard navigation quite early on. Users with lower levels of professional experience may ignore them until they are more experienced.
- People regress faster in their interface knowledge. Do not design only for a high level of experience using interfaces. For example, don t rely on keyboard navigation alone. Even business experts forget how their tools work as soon as they go on vacation – it s hard enough to remember a work password after a week off!
So what s the takeaway from all this?
When I first spoke about this theory at an event in 2018, I had no idea that it would induce me to use the portfolio approach in our design projects.
As with the original theory of risk and return, we take into account the skill level of our users and react differently to projects depending on our position on the effective frontier. The two financial products that I previously mentioned can be represented as follows:

The second product aims to cover a wider range of frontiers. Through custom settings, we address different levels of financial experience, for example by allowing advanced users to display additional financial data.
We have different products for different user contexts. Perhaps, ironically, it is through our open architecture with reuse of the system backend that we have become user-centric and less system-centric. Now we can say that “effective” does not always mean simple, and “simple” does not always mean effective.
Therefore, now more than ever, designers need to tame the complexity of life.
Hope this article helps you!
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