While I can't speak from first hand experience of juggling programming and management jobs, I've observed the same problem in my part-time team leads to believe

While I can't speak from first hand experience of juggling programming and management jobs, I've observed the same problem in my part-time team leads to believe what you say is true. I'd like to add yet another aspect you didn't mention: I've had a couple of experiences in very dynamic work situations where every developer is juggling multiple development jobs at once. If those aren't very well managed (which I've never seen done), the individual jobs/projects will immediately cannibalize each other: The thing that's the most critical right now gets way more attention than anything else, which causes those other things to go unattended for too long, which increases the risk of them becoming critical in turn (either through errors because of rush jobs or because of arbitrary deadlines coming up). The result is constant firefighting. The thing is that juggling management and development jobs basically looks like asking for that to happen (at least to me). Most important "management issues" are more impactful than the development job (especially when done as a rush job) and in my opinion even less likely to be plannable/mechanical in nature. This means that it's even likelier that some tasks will cannibalize the amount of attention others get by themselves and it's never going to be a simple 1/n calculation. And if you maintain that you could reach that kind of multitasking nirvana anyway with enough iron discipline, I'd argue that this discipline should be considered a large multiplying factor of the context switching costs involved.