Yah, I do it for leveling...
While I have the little "Lego Block ramps", it's usually too tricky to get the camper level. I lower the jacks, disconnecting the Fast Gun tie downs, and then level, keeping as much weight on the truck as possible. Typically, I'll get the camper level and then "Lower ALL" at the same time back onto the truck until one shows uneven.
Still working on which way to level first, Front to back and then side by side or 'verse visa'.. hehheh always fun eh?
It's PITA but getting used to it. Also, helps in high winds to stabilize camper.
There are other "Threads" covering this in more detail. Some don't release the Fast Guns/Happy Jack/tied downs as they only need a little lift...
I'm not at that level yet... as you don't want to be lifting up the truck too... just take the camper weight off a bit...
Hope that helps..