I'm a SAHM of slightly older kids. My kids get tired out by swimming, so they're pretty mellow for the rest of the day. For us, it's a nice change of pace to have swimming and no camps--just a chance to have relaxing summer time at home. Yes, they drive me crazy, too. Sometimes we add in a shorter half-day sort of camp.
Every pool is different, so I'd check for the details with someone from your pool. But here's our situation: Pre-team swims M-T-W-Th mornings only. Afternoon practices (three days a week) and Friday morning are just for main swim team. Kids in our pre-swim team don't compete at B meets on Wednesdays, but there are some race opportunities over the course of the season. Those 6-year-olds who are very strong swimmers can be part of the regular swim team, so those kids obviously race every week. Parents of kids on the pre-team have smaller volunteer responsibilities. They often choose to volunteer at the all-team events (pep rallies on Friday afternoons, special breakfasts, etc.), which do include the pre-team. All kids are encouraged to attend meets that they're not swimming in, but most of the time the only kids there and not swimming are siblings. Of course, when you have a home meet, it can be fun to stop by to cheer for a little while and see the "big kids" swim.