Ask what went wrong right after onboarding, not months later
The best time to learn what confused a client during onboarding is right after it happened, while the details are still fresh in their mind. Wait months, and you'll either get vague answers or none at all, because the specific friction points have already faded from memory.
A short question sent shortly after onboarding wraps up — what was confusing, what took longer than it should have — gives you real, usable feedback while it's still sharp. You don't need a long survey. I ask myself this same question right after every onboarding wraps up, before the details fade. One or two direct questions usually get you more honesty than a formal form ever would.
Use what you learn to fix the actual step that tripped someone up, rather than guessing at what might be wrong from the outside looking in.
Try this today: send your most recently onboarded client one short question asking what part of the process felt confusing or slow.