roller

Hey Guys, I am just wondering if anyone ever drags a paint roller against trim by turning it long-ways or diagonally so that it cannot spin. I do this sometimes because it leaves lines on the trim as if applied with a brush and it's generally faster. Anyway...just curious if anyone else did...

I have a commercial office building that I'm doing. It's about 12,000 Sq ft with carpet that is staying. It has a pre hung ceilings in 75% of the rooms. So my question is "since this is my first big commercial job" should I just cut and roll the rooms or try and mask the ceilings and spray...