I'd have to disagree with both statements from all I have seen and experienced...
The slide controllers are counting revolutions to fully open/close... I don't hear the hum of a motor trying to continue to drive the slide at the extreme - I'm just waiting for them to completely turn off and insure the two sides of the slide stay in synch.
I can't picture the stresses on an extended slide while leveling the coach doing anything good. It certainly twists things around as it manipulates the jacks. We've been at our current location just over a month - and things have settled a little... DW wants to re-level... so I'll be pulling in the slides, re-leveling, and extending them again.
The only time I've extended the slides 'not level' has been in my driveway... Completely FLAT - just not completely level (nose down).
Even that I don't do often - as the fridge in my 2014 Hurricane doesn't like being 'not level'.
(The fridge in the 2000 Infinity didn't care...)
__________________
|