I never understood bolt on wheels.
bingo. I carry a 6in adjustable wrench in my repair kit, which can play a lot of havoc for people who think their wheels are secure because they're bolted on. Not that I would steal bikes or parts, that's just bad karma and I would be pissed if someone did that to my bikes.
If you have bolt on wheels and don't have a wrench when you flat... that's luggage on wheels.
As to the original question: You should start to feel resistance when the lever is half closed and it should leave an imprint on your palm when you have fully closed it.
When I feel resistance around half way, I feel like if I keep going it might snap. =S... I'll give it a try and see how it goes.
@Vixtor, you said I could easily swap out a QR axle for a regular nuts and bolts one? HOW?