Arguably, the grav drive and the artificial gravity in the ships are two separate subsytems. You power the grav drive, that's just charging it to jump. The artifical gravity seems to persist for as long as the power plant isn't completely destroyed.
Mild spoilers. There's a few levels where it's zero g. Some random encounters where you raid a enemy ship, it's zero g and when you reach the captain's chair, you turn the gravity back on and all the doohickeys like pencils and mugs fall down in a really satisfying way.
Some people would probably complain because realism, but I've always liked how it's handled in Counter Strike. If you're near a ladder you can just move up and down it relatively quickly, but you also maintain all other character controls. There's no animation and you just like float there, but it works super well for gameplay. Obviously it's not good for a cinematic thing, but for a game that's supposed to be fun to play, it's great.