Andrés, for reference, is an extrovert with low social needs. He's happy with a level of social interaction low enough to distress me and also happy with a level high enough to entirely overwhelm me.
A: . . : : :::|||||||||||||::: : : . . T: . . : : :::|||| social interaction --->(Higher density is better; note the abrupt drop-off at "too much".)
Interacting with people takes a varying amount of energy. The most important factor is how well I know someone or how comfortable I am with them (those aren't quite the same thing, but they're closely correlated). Interacting with someone I don't know well takes a lot more energy than interacting with someone I do know well. Interacting with several people I don't know is lots more effort than interacting with one person I don't know, but interacting with several people I do know is only a little more effort than interacting with one person I know. This makes hosting parties a very efficient source of social interaction -- it takes only slightly more effort than having one or two people over and results in a whole lot of social interaction, giving it a very high return on investment. (Going to parties is less efficient, because other people's parties usually include people I don't know, sometimes in large numbers.)
I have been skating on the edge of cranky-introvert-needs-alone-time-now for the last two weeks. I was all proud of my introversion management at apc16 -- "I'm not overwhelmed at all!" -- but I neglected to figure that unusual social energy expenditure into my plans for the next while, plus I got a number of exciting social situations dropped in my lap all at once (a small number, but they interact in interesting ways). Also I owe a bunch of people e-mail (::waves at some of the people -- most of them, come to think of it::). Now I am feeling weirdly insecure about whether people like me and stuff, which I think is about equal parts (a) having overdone it socially this week and (b) basically all that socializing having been with the same people (who are lovely people I like hanging out with, but who I don't know all that well and who are part of one of the exciting social situations, which makes hanging out with them a little stressier than it might otherwise be). And this isn't letting up anytime soon. Last week I was thinking "Gosh, I haven't seen [long list of specific people] in a while -- time for a party!" but it's going to be a while before previously-planned things let up enough that I'll have the social energy to plan a party.
This is annoying, because I'd like to see the various specific people (hi, people! ::waves at the half of the list who are probably reading this::), but I would also like to avoid messy brain explosions. I think I surface some time in March, which is not so very far away. I shall try to plan ahead enough that there is not too long a gap between previously-scheduled things and theoretical party (busy is good), but I have to leave enough of a gap for my brain to settle down enough to handle planning (not too busy). Must aim carefully!
. . : : :::|||| ^ ^ you are here
 Somebody somewhere sometime between last month and last year explained that when they had a sudden burst of "These people hate me!" in the middle of a convention it meant it was time to go sit quietly in an empty room and coddle the introvert. Thank you, somebody -- it's a very useful signifier, and much less distressing when recognized as a temporary symptom.