Some of that depends on the chassis. Ours is a Workhorse W22, 22.5 rims, so it sits higher off the ground than some other chassis do. In some cases I have to add wood blocks under the jacks. Then you run the risk of lifting the tires off the ground which isn't the best idea, especially the rear tires. I have lifted the tires off the ground, placed blocks off under them then lowered the MH down until the tires are hitting again.
That's not typical, most RV campsites aren't that out of level. Driveways, well they vary a lot.