I've worked in games for close to 15 years, and every studio I've worked on we've played the game very regularly. My current team every person plays the game at least once a week, and more often as we get closer to builds.

In my last project, the gameplay team played every single day.

> Games would be much better if all people making them were forced to spend a few days each month playing the game on middle-of-the-road hardware

How would playing on middle of the road hardware have caught this? The fix to this was to benchmark the load time on the absolute bottom end of hardware, with and without the duplicated logic. Which you'd only do once you have a suspicion that it's going to be faster if you change it...