[aflag]

I frequently hit return rather than typing a period. However, I feel that's not really good practice, as I often see myself sending a lot of small messages which could probably be better summarised with a couple well thought out sentences.

[djur]

It really depends on the context. If people tend to fire off every sentence into the channel as they think, the person who writes a paragraph is going to come off strangely. The reverse is also true.