I would say, if you start on the basis of say, two outfits a day - allowing for food spillages, changing etc and the fact that CH laundries run seven days a week. If he had a minimum of six outfits, then as a start, I think that would be fine. I find things wear very quickly so you may have to "top up" more than you normally would. Things that are severely washed each week fall apart after six months or so depending on their age and quality.
Mummy currently has about five pairs of pyjamas (as these often need to be changed during the night) and this is enough, though they do wear out very fast.
Mummy is also resistant to personal care so I suspect things get pulled about much more, hence shortening their life.
Bear in mind - label everything to avoid losses. Jumpers and cardigans suffer more if they are wool as opposed to synthetic. They just aren't made to be washed and dried so frequently.
Speak to whoever does the laundry at the care home. They are often the most knowlegeable about what works best. Avoid taking in valuables.