My rule of thumb for DD's clothes has been two weeks' worth of clothes. This isn't a simple 14 outfits, though. I look at an actual two weeks of upcoming activities for each season (sleep, school, play, gymnastics, swimming, sports, weddings, parties, etc) and she chooses her favorite items for those activities. She wears most clothes twice before laundering. The rest goes away (charity or friends). When she was younger (and growing so much more rapidly), I would need to fill in quite a few gaps each new season simply because we'd always have a ton of certain things and nothing in other categories. Over the last couple years, I have let family know exactly which clothing items she needs for Christmas and birthday (usually pajamas, swimsuits, and shoes) and they've been terrific about honoring those requests.
I chose two weeks because I keep up with laundry easily and do not wish to HAVE to do a specific load due to some "emergency".
We have a three-bin sorter and I generally wash whichever load is fullest each morning. When none are full enough, I wash towels or sheets. I don't have to do a load of laundry every single day, but I consciously make that decision each morning. My DD is very fashion-conscious and she simply LOVES clothes! She loves fabrics and details and on and on. For me, one week is too few due to laundry issues and a month is too long due to space issues. Two weeks has worked very well for us for about 4-5 years now.
DH hasn't bought into this concept at all. He doesn't own a ton of clothes, though, so I leave him alone. His natural tendency is "what if?" and he leans toward the pack-rack side of things. His world is about to get rocked in this regard. We finally, after nearly nine years of marriage and making do with his old hand-me-down stuff and my childhood furniture, purchased new bedroom furniture and it is arriving in early May. He is already aware that there will be some significant changes going on in our bedroom regarding clothing!
For myself, I think I have reached a good balance. We only have 2-3 seasons, depending on how technical you want to get. For each season, I feel that I have adequate clothing without going overboard. I do find I HAVE to wash certain clothing items of mine more frequently than anything of DD's or DH's. However, I have been losing weight and only own one pair of jeans, black pants, and black capris that fit at any given point. I've been giving away the too-large items as they fall off.
Tops are far more forgiving than bottoms, so I have a lot more of those. I tend to wear them all, though, so I just don't buy any new ones. I go through my clothes about three times a year and donate the ones I no longer like for whatever reason. I probably have too many of the non-staple items, though, like nice dresses. They take up so little space in my closet that I haven't bothered assessing their value in my life, yet. With the new furniture arriving soon, though, I plan to go through our entire bedroom with a fine-tooth comb...