If you're playing against a bad team then yeah go for it but always give everyone a heads up so they can watch their six.
I only play Dom in parties of friends, but half of them are casual players and are not great and tend to lose more gunfights than they win. Their job is to camp their asses on the home flag and to take down any air support. For the rest of us tac insert near the B flag and make sure we don't lose it. That's the best tactic for the team that we are.
If I had a full team of better-skilled players though, I'd definitely push to control all 3 flags as long as possible to really turn the screw.