As a manager of a software team, my goal is to make sure that everyone on the team is completely unblocked to do their job, so even though I only had 6 one on one employee meetings a week, I have meetings with managers, meetings for updates on projects, budgeting meetings, meetings to report to the company executives, getting all the signatures required for large purchases, meetings to discuss planning for future projects, meetings to plan our new process integration, meetings with higher ups to try to correct issues for my team. At one point I had 6 hours of meetings a day, so I think it adds up quickly. I'm not saying my company was efficient, but that's the reality of even a midsize company.

I knew someone who was put into a partial-managerial role, i.e., still did real work, but counted as only half an FTE for the purposes of project planning. The management role was to oversee two people.

So if half a manager is for two people, it's not that great a leap to get to a full-manager for six people.