I sent that tweet out manually. It looks like an automated tweet, though. :) I like to post small tweets sometimes. I think they're easier for people who aren't interested to skim past.
My current limit is not very low. I've posted more than twenty tweets in a single day on many occasions. One way or another, that loses readers. (With lists and checking individual profiles, I pay more attention to some people I follow than others.)
There are many schools of thought on twitter, and many reasons to use twitter. I'm trying to use my account to get more involved in open source. There are so many people and projects in open source that I can't keep track of anywhere near as much information as I'd like. I'm sure others feel the same way.