I have a TT without anything except the stabilizer jacks, and scissor jacks I've added behind the wheels.
I wish I had automatic levelers.
It's about 10 to 30 minutes shorter to setup at a campsite.
Automatice levelers are not perfect. I've seen Class A units with the automatic levelers holding the front (or rear) wheels off the ground to level the rig. Very bad practice. There should always be something under each wheel.
Depending upon the surface your rig sits upon - what was level the day you setup may not be level in a couple days. If we are on dirt, I always extend the stabilizers and jack after a couple days. The ground gets sunken under the weight of the rig, and to maintain the best stability, or to return to near level, I have to adjust.
The principle of automatic leveling is two-fold. The biggest is to lessen the time and effort and equipment needed to get the rig near level. The second important aspect is to take as much weight as reasonably possible off the TT/5er/motorhome suspension.
The percentage of the total weight on the rig springs is the primary source of movement within rig after being setup. Use levelers to get weight off the springs - a more stable rig.
I've also seen a 5er use hydraulic levelers in the manual mode to raise one side of the rig enough to lubricate wheel bearings. Of course, he had a jack and jack stands to make sure the rig wouldn't fall if the hydraulics failed.
It was interesting to see all four wheel bearings repacked/greased and finished in less than 15 minutes. And the rig back to level on the campsite.