I formerly did this - khaki's and polos - but when I changed jobs to a company that required dress pants and Oxford shirts, I mixed it up a bit. I call it my "office drone uniform". Now I have between 10-15 long-sleeved dress shirts that I rotate, and 8-10 pairs of dress pants. I have shirts in a mixture of blues, greys and whites, and mostly dark pants (blues, greys, blacks). Mostly bought at the local thrift store during one of their 50% off sales. Whenever I buy a new shirt, I donate one to the store. They ALL interchange with each other, and by having more shirts than pants, they're always rotating.
I wear clean t-shirt/underwear/socks every day. I take the first shirt off the LEFT, and the first pair of pants off the LEFT.
At the end of the day, I get home, and IMMEDIATELY change into jeans - hanging the shirt and pants du-jour on the RIGHT.
I launder them as the collars show signs of wear/staining - usually every-other month. Meaning I wear the 'outfits' 3 times between washings. I've been doing this now for 4 years, and look professional every day.