Well, others here are more knowledgeable than I, but I would say that it depends on several factors. One being thee type of lure used, two being the type of set used, three being the outside air temp.
If using a dirt hole set, I would say a glob the size of a pea should be enough. Put bait in hole (if using it) and then your glob of lure down the hole make sure your hole is deep enough so the critter has to "work" the set to see what that lovely smell in there is coming from. Some folks put a glob of sheep's wool on top of the bait and lure for eye appeal.
It depends and mix it up some. Put just some lure in the bottom of the hole with a squirt of urine down the hole. Mix it up.
Use Bait & lure at some sets, some with just lure, some with lure and urine, but most importantly make your sets where the critters are traveling (look for sign - scat, tracks, etc.) and then be patient.
Make sure you treat your traps to help eliminate as much odor as possible.
Just don't give up!
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I am MAN/BEAR/PIG! Half Man, Half Bear, Half Pig!