Keystone Cougar HC design flaw with rear cabinets.

on our trailer, I always open the slides about 6 inches, about enough to get between them, then walk back and look at both sides to make sure doors, drawers are closed, and nothing has fallen to interfere with the slides.

Then I move them the rest of the way out.

I've seen many trailers that have drawers, doors, chairs, etc. that can end up interfering with the slides when they extend or retract.