Correct. New posters have lower editing time. I believe the standard time is 1 hour. Promoted users can edit up to 2 hours later.
Defenders of Defoko and Supporters have unlimited editing time. That being said some boards, like the UtaSwap, Help Section, Creative Writing, etc. have their own edit times. None are shorter than the default 1/2 hours and some are even unlimited for all members.
Really depends where you are posting.