Doom Eternal staff "were crunching pretty hard most of last year" to hit the game's original November 2019 launch date.
Quake and Wolfenstein developer id Software eventually pushed Doom Eternal back to 20th March 2020 - a delay of four months.
"It goes in phases," executive producer Marty Stratton told VG247 of last year's overtime. "We'll have one group of people crunching so the next group of people are teed up properly. As they get done, they may need to crunch a little bit.
"We really truly do try and be very respectful of peoples' time and lives. We have very dedicated people that just choose to work a lot in many cases. It was nice because we want the game to be perfect. We want it to live up to our expectations and consumer expectations."
Doom Eternal was complete by the time its delay was announced, just six weeks before it was due to hit shop shelves.
The intervening period has instead allowed id to "fix a tonne more bugs" and polish the game after testing found balance issues and exploits.
And surely more time means less need to crunch? Well.
"[A delay] takes a little bit of the steam and pressure out," Stratton concluded, "but it's almost one of those things where we'll push it even harder to get even more just as tight as it possibly can be."
It feels a similar situation to the recently-delayed Cyberpunk 2077, whose developer CD Projekt Red admitted the extra five months of time it now had would be used to continue crunch "to some degree".
For more on the game, Digital Foundry's John Linneman recently took a look at some of Doom Eternal's new tech.