When actively using the RV, I have the jacks down - before deploying the slides.
Partly for the slides... Partly for the general stabilizing. (DW notices when they are not down...)
I never deploy/retract jacks with slides out.. the twists and torques as they move can't be good for open slides.
At home, I have opened slides with jacks up while on driveway... For loading/unloading...
To me not an issue if flat and reasonably level...
But with auto jacks so easy to use, I wouldn't camp in it without them.
Not yet retired...
Florida (Michigan transplant)
2014 Hurricane 32A
2000 Infinity (previous)