Kiarra
Former Betta Breeder
It's really a personal choice, though I think it's much harder on the father when you leave them in there. My Delta male from not the last spawn, but the one before it, was left in with his fry for about a week before I took him out at the first water change. He COULD NOT handle being separated at all. He stopped eating, and he just got so depressed that he caught something, even though I was keeping his water very clean. He died quickly after that.
But, then again, I left the Doubletail from my most recent spawn in for just shy of a week, and he came out and did fine. Didn't get sick, and didn't mope at all.
I've also pulled fathers right after the fry were free-swimming, and the fry did fine. But I've left the fathers in with other spawns, and they did fine, too. So it really does come down to a matter of your preference, and what you're comfortable with.
But, then again, I left the Doubletail from my most recent spawn in for just shy of a week, and he came out and did fine. Didn't get sick, and didn't mope at all.
I've also pulled fathers right after the fry were free-swimming, and the fry did fine. But I've left the fathers in with other spawns, and they did fine, too. So it really does come down to a matter of your preference, and what you're comfortable with.