4 to 5 hours is achievable and easy if you are aligned with your work and team and find it energizing. With a bad team, bad money, or bad product, downright near impossible to care enough for it.
Meetings themselves are the problem and what I'm suggesting are the problem. I don't think team alignment is related to the disruptive havoc caused by meetings. We have a lot of evidence that it takes a long time for a mind to refocus on a task once disturbed.
I say it's impressive you can crank out that level of focused work because I can't get a long stretch of uninterrupted time that you can. Maybe you have fewer meetings?
It's two 2-hour work blocks a day, one in the morning and one in the afternoon. Yes, you have to aggressively block other activities. Working in small teams with similar goals and prescheduled sync points has helped a lot.
