Where I come from (the 20th century), we prefer to spell things out in full. With today's smartphones (featuring autofill predictive text entry), it doesn't take any extra time, and most people aren't paying by the character :)

Personally, I hardly ever use abbreviations, but I think it’s an age issue (I’m over 60). With my stepkids, or with my (mostly younger) online language community buddies, I will use things like btw, lol, imho, but with friends my age, rarely.