I've always started off the encounter with everybody getting a free monster knowledge check. (Talking both 5E and PF2 here)Hmmmm I'm not sure that no rule is a better solution than using an action, in the 5e games I've played in the DM has insisted its an action (obviously with exceptions), which i think is a fair shout.
Success gives pretty much everything you need to know. You seldom need more than one success.
If nobody succeeds, the party members might well spend an action on a second (third...) attempt.
But likely only if the fighters learn the monster is highly resistant to regular attacks. Remember that in many cases, trial and error works well enough.
After all, the overwhelming majority of monsters abide by the classic rule "if it bleeds you can kill it"!
So just attacking it often tells you what you need to know. And in most cases you deal at least some damage! That alone makes the action worthwhile, and likely a better deal than wasting time with monster knowledge.