What an interview guide actually is
Yes, in almost every case.
Writing an interview guide before you talk to users is one of the cheapest ways to protect the quality of what you learn.
A guide is not a script you read aloud.
It is a short list of topics and open-ended questions that keeps the conversation on the things you actually need to find out.
This article explains what a guide is, why skipping it is risky, and how to build a simple one in a single working session.
It also covers when a guide matters less, so you can judge your own situation rather than follow a rule blindly.
In discovery research, most useful interviews are semistructured.
A semistructured interview uses a discussion guide that the interviewer applies flexibly, according to Nielsen Norman Group.
Questions can be asked in any order, some can be skipped, and new questions can be added on the spot.
That differs from an interview script, used in structured interviews and followed more rigidly.
Nielsen Norman Group describes the guide as paving the way for a deep, free-flowing conversation.
So the guide is a safety net, not a cage.
It sits beside you during the call.
You glance at it to check coverage, then return your attention to the person talking.
Why going in unprepared is risky
The main risks of interviewing without a guide are practical, not theoretical.
Nielsen Norman Group names two risks: asking leading questions while improvising, and failing to cover research-question topics in every interview.
Either one can compromise the validity of your data.
Their guide-writing article notes that constructing a good guide can be tricky and time-consuming.
Some people spend a full day crafting one.
For a founder or freelancer, that risk shows up in a familiar way.
You finish five conversations, feel encouraged, and then realize each person answered slightly different questions.
You cannot compare their answers, because you never asked the same things.
A guide fixes that without making the conversation stiff.
There is a second, earlier risk worth naming.