My (only child) son is also a social butterfly... if he had HIS druthers, we'd have people over 24/7. It doesn't matter how much he's around others throughout the day... he just LOVES being around people. He gets energy from it. CLASSIC extrovert.
So that said... I try and keep it down to 2 a week tops (or we just get massively behind) ... but we'll also go several weeks w/out playdates just because either a) we're busy or b) they're busy.
We are in TONS of activities, but it doesn't help. My son just loves being around people.
In talking with other parents, the 3 biggest obstacles in our area tend to be:
- family time
Most of the families we know not only have built in playdates with other kids (sibs), but both parents work. So that means that M-F playdates are all but impossible. School-Daycare-Dinner-Homework-Bath-Bed. While rearranging daycare is possible for some families, most of the time it's not. Then weekends get REALLY busy as families try and spend time together, set up playdates, go to sports games, church/religious obligations, extended family time, adult friend time / girls or guys nights out/ datenights, saturday birthday parties, and trying to rotate playdates not only between friends to keep it kind of fair/even, but also between sibs for the same reason. Assuming one of their kids has 3-5 good friends/besties... and they actually rotated to try and see all of them, that means only being able to playdate once a month per family. When sibs get involved it gets even trickier... because some families can handle multiple friends over at the same time, and some can't.
Ditto... we tend to be the ones reaching out. Which is ironic, because I'm actually pretty introverted. Same token, however, our schedule tends to be the most "flexible". All of the above, plus as a family of an only, we don't have to also take into account other sibs schedules (like naps, etc.).
I figure it's a temporary thing. At age 8, he and most of his friends, still have to arrange things through US. Which means instead of just knocking next door (we don't have that kind of neighborhood either), they have to deal with 2 entire family's schedules. And instead of just being able to phone themselves and set up a meetup at a local park, etc (like around age 12), they still have to be supervised playdates.
For myself, we've had to turn down playdates in the past because of prior commitments... but I LOVE it when other people to the leg work/ are calling me.