Really? I see this all the time.
You can especially see it on airlines that have signs for group lines labeled 1-5 permanently displayed at the gate. As soon as the announcement goes out that the boarding process will begin shortly, a dozen people from Groups 4 and 5 will rush to their lines.
I've never understood this. I just sit back and relax until the mayhem calms down and then I just stroll on at the back of my group.
We all leave at the same time, so what's the rush? Then again, I don't ever travel with just a carry-on bag.
If you're boarding in a late group, overhead space will likely be at a premium, so you want the best chance to claim that space and not have to gate check.
I don’t know if it’s anticipatory anxiety or what, but I seemingly observe half the passengers stand and get in line at first call. And even queue up for the queued boarding calls.
I always get on toward the end and never had an issue finding space, but I understand it’s aircraft and airline dependent.
If you don't get on fairly early after them, its likely you won't have a place to put your carry on, or it will end up being in the back of the plane/whatever forcing you to wait longer to get off.