Practise the FDE customer simulation round in 60 minutes: spend the first ten minutes only asking questions

FDE Times published a hands-on guide on October 22 for practising the customer simulation round, the interview where someone plays a vague or difficult customer. Its core advice is that strong candidates use the first ten minutes of the call only for questions, because the round mainly tests whether you find the real problem before you start building, and customers rarely state their true constraints up front. The guide notes that Cognition's case study round, for example, has an interviewer play a non-technical or difficult customer.

The drill runs 10 minutes of preparation, a 45-minute call and 5 minutes of scoring; the guide says these timings are for practice, not taken from any one company's loop. A friend plays the customer from a hidden role card, such as a hypothetical logistics firm whose data can't leave internal systems, whose support team can't code, and which has a board demo in four weeks. The role-player reveals each constraint only when asked directly, then moves the goalposts at minutes 20 and 35.

Once the constraints are out, the guide says to state them aloud and propose the smallest proof of concept that still delivers value rather than a full architecture. When scope changes, accept it but spell out the impact on the timeline, since scope that doubles needs a new quote. Useful prep questions include what a "win" looks like for the customer this month and how people cope today when the current system breaks.

Why it matters: customer discovery and scope control are the skills that separate FDEs from other engineers, and they are hard to practise alone. A cheap, repeatable drill like this gives candidates a way to rehearse the round most likely to trip up strong coders.