Most of your gasoline coaches use blocks because they do not have air bags that can lower the motorhome down and give the levelers more inches lifting. Gasoline motorhomes have either leaf or coil springs. So in order to give those levelers more inches to lift higher, they add blocks under the pads. So motor homes the levelers are so short they have to add blocks under the wheels.
Not to often do you use blocks on diesel pushers. I have the Quadra (BigFoot) and I really love these levelers. You can operate them individually or all four at once and they have a long solid extension hydraulic ram. None of those springs that come on cheaper levelers for the return of the jack. About the only time a diesel pusher owner needs extra pads which would have to be bigger then the jack pad is when the soil is very soft.