Jase,
Believe me, I've read the posts here; what you scrim (all, top, left, right, bottom) is a totally different thread. I even remember someone doing a poll here, asking what areas of the window we scrim.
But, generally, when using ladders, I only scrim areas that are comfortable to reach; I won't over-reach to scrim far left or right hand edges of windows; nor the tops of them.
On ground floor windows, I'll be a little more carefull; but you'll find the better your washing and squeegying gets; the less you'll scrim.
Some windows I don't bother, as there's no need.
I think it just comes with experience and the type of windows you're doing; some are better than others.
When working trad, I'll only clean frames when they noticeably look dirty; but I clean all the sills; I think this is important.