Moosedog and AnimalK have given good advise. I have several SWK's and I generally follow this routine.

Unless you really sweat badly, or craw in the mud, a Kilt will last much longer between washing than pants. I'm thinking at least 12 to 15 wearings between washing. And hang correctly and let the fabric rest about a week between wearings. That's why you need about 8 kilts to start off. 3 low-end casuals, 3 high-end casuals and 2 tanks. Then build from there....... worked for me.