Just finished indoc, 9 days plus travel days.
I brought one pair of dress shoes, 3 pairs of slacks and 6 button down shirts/socks/uw plus one pair of jeans and a bunch of t-shirts for casual evenings, clothes to sleep in, plus the clothes I had on during travel day.
I stuffed all of this in my Briggs domestic carry on spinner (which has a bit less interior space than the 2 wheel unit), but I needed to expand it fully. Compressed it is a legal carry on but won't fit in the bins of the 145s and other 50 seaters. Our 175's can hold a legal carry on in the bins but my bag was expanded beyond the legal domestic carry on size so I had to gate check it but it's actually more convenient to gate check than it is to sluff on down to baggage claim.
On Friday evening (after four days of training) I took my pants and shirts to a local dry cleaner (Sunshine). That was ready on Monday by 4PM.
On Saturday I took all the remainder of my clothes / socks / uw / jeans to a laundromat called Pepper's Express. It's about 10 minutes south of the hotels. Owner is a former XJT FA and really nice, and place is only about 5 months old so it's brand new. Bathrooms are clean, so while you do a few loads you can leave one or two yourself.
Moral of the story: pack for about 5 or maybe 6 days and refresh with a trip to dry cleaning and a laundromat.