Letting product dry/sit on MF

[BMW335i]

SO I don't always immediately wash my MF's, I allow them to accumulate so I don't waste water washing one MF in the wash. Is it bad to allow product (sealant, QD, dirt, etc.) to 'sit' on the towels for a few days? Will washing remove the leftover product?

 

[greg'sgoat]

I have noticed mine will stain if I don't wash right away. The longer I wait, the harder the stain is to remove. I haven't noticed a decrease in the actual MF. Still plush in the areas of the stain, still works like it should (no excess product). It would be great to wash everytime I use it, but that won't happen.