The only way hiring people will help you develop faster is if either:
ramp up time is insignificant compared to project time and you don’t hire so many you hit communication overhead.
you’re hiring people to do all the other stuff the people working on the project were also doing. I don’t think game devs typically have four systems in the maintenance lifecycle while they also develop new stuff, so that means you’re hiring a few IT folks to wrangle the weird office issues programmers wander off and deal with, a sysadmin, and like, 45 lunch delivery people.
I’ve had the first one work once, when we had a year+ project timeline. Hired one person, took them a week to get started, a month to be properly contributing and maybe another to be up to speed. We were a four person team, so not much overhead.
The second one is the dream of every manager who finds themselves with a contractor budget. I have yet to see it work the way they want. The only way I’ve seen it work is when you tell an established team that some other teams maintenance project is now their maintenance project, and eat the sharp increase in timelines for that maintenance work.