I buy 4 sets of sheets (with 4 pillowcases each) and 5 sets of towels all the same color for two apartments. I'm always missing a pillowcase day of making the bed so the extra help. Towels...I end up throwing them out from time to time because someone has used self-tanner or dried their dyed hair...Occasionally I'll be missing a handtowel or washcloth. I know I've come home from a hotel with one inadvertently stuck in a corner of my suitcase. If you buy them 5 sets at a time you save a ton of money and it becomes a non-issue.
I recently started adding a $25 linen fee to each booking. I don't think anyone even noticed but it helps me a ton because I provide a washer and dryer with top of the line detergents and sundries bags, etc. It eliminates all of the need for closely monitoring and driving myself crazy.