Meetings? Doing more than two back-to-back, hour-long meetings is an ordeal if you want a productive meeting. You can sit there and stare into space for far longer, or just keep minimum attention. But intelligent debate with multiple individuals for longer than that is hard to pull off, especially if you also want to get the productive work as mentioned above.
Meetings of the "just being present" and responding various, random emails that need little care? Feel free to spend 10 hours a day on those, for sure.
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?
This does not include meetings, communication etc.
This is essentially the time spent towards a tangible deliverable.