Did you kill all bosses in your first playthroughs?

My brother guided me through the games (yes all of them) so I didn’t miss any bosses my first go through, and I beat them all on a first playthrough. But I see people who have played the game several times and haven’t killed all bosses. How many playthroughs did it take you to kill all bosses in a From game?

My brother guided me through the games (yes all of them) so I didn’t miss any bosses my first go through, and I beat them all on a first playthrough. But I see people who have played the game several times and haven’t killed all bosses. How many playthroughs did it take you to kill all bosses in a From game?