My understanding is that in HS it's always one tweet. So that's what I do. However, I agree about the pile up and any kind of heated confrontation. And I'll sound a longer whistle when signaling a time out.
Having said that, I like the double- (sometimes triple- depending on the ratio of show to boat
) tweet on violations. Like the open hand v. closed fist, it communicates something subtle but important. When I'm watching a college game and hear the multi-tweet, I have a pretty good idea of what's being called even before it gets signalled. I think it's a good communications tool.