The company I work for at the moment has two values/myths that have worked really well at preventing situations like this. Early on, just before I joined at around the 150 person stage, the employees self organized values. One of these was Daytime is Precious. Interestingly it was applied equally to the idea of don't waste time (meetings etc) and to the idea that everyone has a life outside of work. The second was the idea that teams are anonymous, and decide themselves what they work on.

In reality these are ignored at times when required. But they're so embedded in company culture that you need a pretty good reason to do so and more importantly most employees are comfortable challenging management when they do.

I'm not sure how to replicate this but letting employees set the company values once you get to a certain size is likely a good call.