Prepare once, reuse everywhere: an interview system

Build an evidence bank once, then prepare for any interview in ninety minutes: the four research questions, the story index, and the rehearsal that works.

The short answer: Most interview preparation is wasted because it is thrown away afterwards. The system that fixes it has two halves: an evidence bank you build once and keep forever, and a ninety-minute routine you run per interview. The bank holds twelve to fifteen stories from your own work, each written down while you still remember the detail. The routine covers four research questions about the employer, choosing which stories to lead with, and one rehearsal out loud. After the third interview the bank is doing most of the work and preparation drops to under an hour — which is the difference between preparing properly for six interviews and preparing properly for one.

Key points

Build the evidence bank once: twelve to fifteen written stories covering conflict, failure, influence, pressure, initiative and analysis.
Per-interview work is selection and research, not composition — you are choosing from material you already wrote, not inventing it under pressure.
Four research questions cover almost every employer: what they sell, what changed recently, who this team serves, and what the role is really for.
One rehearsal out loud is worth five silent read-throughs, because the failure mode is fluency under mild pressure rather than recall.

The evidence bank

The bank is a single document with one entry per story from your own work. Each entry is a few lines: the situation, what made it hard, what you specifically did, what happened, and what you would do differently. That last line is the one people skip and the one interviewers reliably probe.

Cover the categories rather than the jobs. Behavioural questions come from a small set of themes, and a bank organised by theme is searchable under pressure in a way a bank organised chronologically is not.

Conflict — a disagreement with a colleague, a manager or a stakeholder, and how it resolved.
Failure — something that genuinely did not work, owned without deflection.
Influence — persuading someone with no obligation to agree with you.
Pressure — a deadline, an incident, a period of sustained load.
Initiative — something that existed because you started it.
Analysis — a decision you reached from data, including what the data could not tell you.
Ambiguity — a situation where the brief was unclear and you had to choose anyway.

The four research questions

Employer research goes wrong in a predictable way: people read the About page and arrive able to recite the founding year. What an interviewer notices is understanding of the business, and four questions get you there for almost any employer in forty minutes.

What do they actually sell, and to whom? Not the mission statement — the revenue. For a bank, which divisions and which customers. What each division does is the map for this.
What has changed in the last year? A results announcement, an acquisition, a new market, a regulatory finding, a restructure. This is where your specific opening sentence comes from.
Who does this team serve internally, and what do they complain about? Every function has an internal customer, and the job usually exists because that customer is not fully served.
Why does this role exist right now? Growth, backfill, a new obligation, a project. The posting usually says, indirectly, and it tells you what success in the first six months looks like.

Those four answers also generate the questions you ask at the end, which are scored — see questions to ask an interviewer.

The ninety-minute routine

What to do the day before an interview
Block	Time	Output
Research	40 min	Answers to the four questions, in writing
Story selection	20 min	Six stories chosen and mapped to likely themes
Adapt	10 min	Each story's emphasis shifted toward this role
Rehearse aloud	20 min	Three stories spoken end to end, timed

Ninety minutes. The rehearsal block is the one people cut, and it is the one that changes the interview.

Rehearse out loud, standing up, with a timer. A story that reads well in two minutes often takes four when spoken, and discovering that in the room is expensive. You are not memorising; you are finding out where the sentence structure collapses and how long you actually take.

Frequently asked questions

How many stories do I actually need?

Twelve to fifteen covers almost every behavioural question you will meet, because the same story answers several questions from different angles. A project that went wrong is a failure story, a resilience story, a stakeholder story and a lesson-learned story depending on which part you emphasise. Beyond about fifteen you are storing material you will never reach for.

How long should I spend preparing for one interview?

Ninety minutes for the first interview with a new employer, less once the bank exists and you have researched them before. Split it roughly: forty minutes on research, thirty on selecting and adapting stories, twenty on rehearsing out loud. Spending six hours is usually a sign that the evidence bank does not exist yet and you are building it under deadline.

Is it worth writing answers out in full?

Write the stories out in full once, when you build the bank. Do not write out answers to specific questions in full, and never memorise them — a memorised answer is audible, it collapses the moment the interviewer asks something adjacent, and it stops you listening to what was actually asked. Bullet points per story, then speak from them.