I work at a very young start-up company. We have had turn-over rates (mass resignation of staff, thrice) in the past but changes in the system have led to a more a stable employee retention and better technical-skilled employees. We do games, and I don't know with other software fields, but the "death march" is quite popular in our field.
My boss believes that the only way for us to catch-up to top companies is to exert more effort, which generally translates to more time working. Hence, we've had a culture of working a lot of hours (we work an average of 65 hours a week, peaking up to 90hours a week).
Our deadlines are either very difficult and sometimes impossible (since the team is pretty young) but our management sets deadlines at the "if people at company X can do this in X days, we can do it too"
I personally believe that raising team efficiency is one of the factors that can help eliminate too much overtime.
I've seen my subordinates/junior staff often not focused enough during the day, but I don't know how to objectively measure this (I've seen questions here relating to KPI's, or key performance indicators).
I'm in a position where I have good relations with my boss (our CEO), the management and the entire team and I believe they're more than willing enough to hear out what I have to say.
How can I approach this in a way that is beneficial for both the staff and the company?