I voted for one thread.
While everyone is free to do their own thread, pre-, during, or post-trip, we started this because there are LOTS of people who don't want to do a thread of their own about the trip. Maybe they're up for a post or two, some pictures, and a check-in update now and again. But the commitment of a thread of their own can be more work than folks want to do while on vacation. And life gets busy once you get home again. So we started the sticky monthly thread for folks to have a home for a post or pic or update.
If folks want to avoid the pre-trip chatter, much of it can be skipped by (using April as an example) NOT opening the April thread until at least April 1 and jumping to the posts in it that are April 1 or later. While you won't avoid ALL the pre-trip excitement, you'll skip a lot of it.
That's my opinion and it's worth what you paid for it.
Bama Ed