Basic Competence

[Iyrnwaen]

But it's usually not a good idea to have the team sitting on the checkpoint.

No, it's almost always a good idea to stack 5 on the point for a quick cap after you win the first engagement.
Cap speed is based on how many players you have on the point vs how many enemy players are on the point.
If you have 5 and they have 0, the point caps in a few seconds. If you only have 1, it takes forever and can be solo contested.
If you have 1 on point, 1 or 2 standing near the point but not on it, and 2 or 3 running around trying to pick off stragglers,
you're creating an opportunity for your own people to get picked off or for a single opponent to freeze cap progress,
and you're giving the enemy team loads of extra time to regroup and contest.