Depends on the day... I work from home most of the time, which helps in that I can overlap work and homewear for the most part.
So most days: Start in PJs. Change to workout clothes (which doubles for 'active' chores around the house). Wash up and change to 'work'/at-home clothes, which is casual. Then, if going out on errands or to visit, dress up a bit (a little smarter for visiting). Finally, back in PJs. So, yeah, four changes basically.
Some winter days, I get by on three; much of the year, I need to shower and change by evening anyway, because it's THAT hot and humid.
Some days get more complicated. The days which involve dinner at a friend's or a party, so eveningwear. Or the days we might go out for dinner and a movie, so smarter casualwear. Or those that involve meetings for work, that require calling in smart business casuals, which will be off as soon as I'm back home, because I need comfier clothes for the at-home work setup (can't sit cross-legged on the floor in pencil skirts!). Or when I'm entertaining at home. So that's an extra change, say 5-6 times a month.
Travelling assignments make for the most chop and change. First, airplane-friendly clothes --- comfy, stretchy, but smart enough for business and practical enough for running about outdoors as might not get a chance to change before meetings/tours/interviews. Next, maybe change for a casual tour of the place, or for a visit to the spa. Or else dress up for a welcome lunch! Third, typically dress to see the sights. Fourth, back for a change to eveningwear. Five: Gym/swimwear whenever I can fit those activities in. Finally, night clothes. So some of these days can involve 5-6 changes :-/ but I try and restrict it to no more than four, carrying a few layers in a large handbag to switch out if necessary, from tourist's-day-out-on-town to formal dinner or 'event'. It really helps that casual is the norm for this industry (media/publishing) and I'm more often the observer than standing in the spotlight. Otherwise it would be hard to travel light.