If you are an experienced window cleaner who only uses a couple of scrims a day then you should only use maybe two dry ones a day.
Now I've been using the microfibre cloths for a long time I've found that just like a scrim, when slightly damp they still work very well for buffing.
When I first bought micro's they were a tenner each, oh boy, the price of them has really dropped now!
Some years back, and I mean something like about 18 years ago, you often had a very wide choice of graded scrim to chose from, from very heavy duty to quick-to-break-in.
Then as time passed, so did the options, and the price of the bloody things climbed steadily, they went up to almost a fiver each.
With the internet of course the prices have fallen again, but now the microfibre is so close to the price of a scrim I can't see the point of getting scrim at all.
And as for washing...I just bang them in with anything else, always a low temp wash, but never use a softener!!
And don't bother with the tiny micro's!! in the winter, a couple of wipes and they are wet and useless
Ian