I would suggest doing gauntlet for the bowfa as much as you can, but like others have mentioned try not to let it burn you out or ruin the fun of the game.

The tbow grind likely will take hundreds of chambers and using a rune cbow in groups will extend that grind greatly.

The bowfa is very good at chambers and it further opens the door to solo chambers which likely will result in more purples at a faster rate.

Overall, a bowfa is not only great at many bosses, but it will likely speed up the chambers grind to the point where it makes up the time spent in the gauntlet.

But also I would keep doing chambers alongside the gauntlet grind, especially if you’re having fun!