Honestly, it varies by the student. Some of them have past experiences. Some of them do the latter thing you said - "It feels like you want me to… (whatever)". Some of them we'll say six or seven things and one of them will stick (in those cases I've often pre-emptively told the student what the mechanics are, but that any feels we try will be to see which "click" best, but to know that they're all attempting to produce the same result - just because we say a second or third or fourth "feel" doesn't mean we're saying to ALSO do that feel, but rather to try it instead.).
Some people have very little body awareness. They're sometimes the most difficult people to teach. If you're working on decreasing flex in their trail knee, they might snap it straight right away, or keep it flexed really long then snap it straight at the end, perhaps. It can be a mess. They'll often have to ask you "did I do it?" and it's tough, because they basically lack "feel" (body awareness) so producing proper mechanics from these types is difficult. Nowhere near impossible, but it requires more thought and effort.