I remember news coming out about it in the early 2010s that a study showed that crunching reduces productivity drastically, to the point that even (only) two weeks of crunching will negate the additional work time. Curiously, some game companies at the time were crunching for a year or longer. I believe the statistic reported was that productivity commonly was reduced to 10% normal when crunching.

James Stephanie Sterling did a video about it, which is how the news came to me.

ETA: Typically, the problem is that game publishers will sometimes set impossible deadlines, or, if a game is on schedule to come out on time, the publisher will push the release date forward to an earlier release season. This was before the trend towards live service games, which was its own nightmare since the game would be released incomplete, but with a roadmap of expected features. Hence the development teams were perpetually behind and often were perpetually crunched. (/ETA)

Studies from the aughts (not necessarily related to game development) regarding the effect of micromanagement tools used on the workforce (e.g. mouse movement monitoring and keylogging) came earlier, noting that the time wasted by workers (under the label of time theft ) doing activities such as going to the bathroom, checking social media, talking to loved ones on the phone, getting coffee, etc. were more than offset by the increase in productivity when workers were allowed to do these things. (Slacking workers do exist, but they are starkly the exception. And large companies typically have a significantly greater number of bullshit jobs -- workers tasked with busywork that doesn't actually serve administration or the profit motive -- than they have shirkers.)