I don't use a harness every time either. I've had them installed in the stand before, though. I went to using all 2 man ladder stands, not only for extra room, but also for the weight rating. I always have help setting them up, and I go up while there's help there and get everything anchored in, and jump on it and jiggle it and retighten everything.
My last old school treestand was in a tree behind my house. A buddy wanted to borrow it to go bear hunting. I climbed up the screw-in steps 20' up and as I started to take the ratchet straps off, one of the steps pulled out of the tree...and then the other one. Fortunately I was bear hugging the tree. The bottom of my thighs continued to take out each and every one of those fuggin screw-in steps all the way to the ground. Unfortunately, I was wearing shorts and no shirt. Legs and chest were rashed pretty bad. Bottom of my thighs were black and blue for 2 weeks from hitting every tree step on the way down. I laugh about it now, but it hurt like a mfer when it happened