Most tRPGs have something of a knowledge skill system. Use that. This is a dual failing when this problem happens.
GMs should call for or make knowledge checks when there is a 'right way' to do a given X. If that fails, a player should remember to say "Can I make a check against 'Knows XYZ' to see if I recall anything on how to handle this situation?
- then give appropriate clues for the level of success or failure on that.
Systems without that level of granularity require ad-hoc rulings to the same basic point.
An idea (or maybe an observation) I have about knowledge skill systems is that groups can choose between
Knowledge skill checks determine whether some fiction the player contributes is true; OR
Knowledge skill use by a player invites their GM to contribute some fiction.
Fiction, once made true, persists. Framed in terms of the OP, the options could play out as
Player says that digging a pit on a game trail is the best way to catch a watzit. GM calls for a knowledge skill check. Success means that as it turns out, in this world watzits are best caught by digging pits.
Player says they (as their character) would know how to catch a watzit because they have skill or background X. Negotiation may be required to agree applicability, but let's say they agree that Watzit's are supernatural creatures and those are in scope for skill or background X. A successful check forces GM to contribute some fiction - the best way to catch one is to wait in the watzit tree. (With interesting opportunities around how to handle failed checks e.g. the fiction can turn out to be troublesomely true, dangerously false, or I suppose just false.)
GM pre-authoring watzit-catching fiction either rules out the first option (in which case, why not just disclose it?) or remains contingent (i.e. is subject to change until it enters campaign canon via either option.) Where a knowledge skill check is called for to force GM to disclose something they
pre-authored, that can be viewed as falling into the second option (does it really matter
when GM authors it?)