I am a new hire at my company, and in an managerial position. It’s a fairly high volume, stressful work environment, and my predecessor had a breakdown and left. (I didn’t know all this going into the job). Apparently, he used to run his team pretty hard and would expect them in at 7 am and work until 8-10 pm in the evenings, and some weekends. No other departments in this company work the same way, it’s just the culture of this group. So I have a team who is terrified, works incredibly hard, and has been conditioned to live and die by their manager’s work schedule. There have been several instances where I know they don’t have much to do and it’s 7 pm, but they are all still here. I’ve tried telling them that as long as their work is done, I prefer them to leave on time, but the message is not getting across.
Aside from the initial WTH was wrong with your predecessor, you have to understand that this is a specific group of people who have been under the thumb of basically a tyrant. You don’t mention the average ages or tenure of the group, but I am going to assume that some of the staff are older and have been here for a while, and that there are a few positions that keep a fairly high turnover.
Make it clear to them that work/life balance is important (because it is!) and you want them out of there by a reasonable timeframe, barring work emergencies/certain deadlines. Lead by example, taking your laptop home if necessary. If this continues, sit the team down and make sure everyone understands expectations, and that the rules of this game don’t include whoever staying the latest winning!