Lots of opinions, here's some facts...
On a prior 5th wheel a few years ago, I ran the main kitchen slide out when hooked to the truck. It was not level, but it was also not really unlevel.
Long story short, burned out one of the Schwintek motors and we were in the middle of a week long trip through the Canadian Rockies, several hours away from any service center. Ask me now how I know how to disable slide motors so that you can manually move them in and out
And, ask me how much fun it is to have to move them in and out manually so that I could keep my promise to my DW that we would celebrate our anniversary by following our honeymoon route for the entire week...
And, if you like, ask me how much that experiment cost... the tech reminded me that they told me not to do that, and that the manual clearly indicates that you should level first.
BTW, it was not the first time I had opened slides without leveling first, but it was the last.
Obviously now I am firmly in the camp of disconnect, finish the auto level, then open the slides; always.
Of course, if you want to conduct your own experiments I would recommend you keep a log book. It might provide interesting data points to try to compare notes and see how many times you can conduct the experiment before an expensive repair. I think I didn't make it more than about 6 or 8... maybe you might set a record and make it to 9 or 10!
Brad