Why use scrim to wipe the sills ? Scrim is for detailing round the rubbers if needed then run your squeegee along the sill to get most of the water off then wipe over with your wet cloth/microfibre job done takes seconds.
I run the scrim over it, there's no detailing that gets done round the edges either. You might think it takes seconds but add all that up over a week and itl add alot more time on than you think. That's just how they get done around here, I'm not going to try argue that wiping it all away doesn't look better because it does, I'm not going to make the job last any longer than I have to though. I get no complaints leaving it either btw.