while I hate it when I plan for a party and I get "oh, I'm busy that day", "yeah, I'm doing something else" and end up scrapping because everyone's "too busy", I'm one of the bad ones for being lax in replying to invites.

However, I don't ever NOT reply and then just show up. I'll let the host know one way or the other before the event, but it could be a fairly short notice unless I know for sure that I can attend.

I'm also bad for not thanking people right away. I mean to, but I seem to just be super lazy/postpone/avoid and not end up doing it for several days/weeks.