focus requires a rigorous contract
Balancing many disparate tasks is good for my morale (“Wow! If I get bored with this one thing, I can just do something else!”), but feeling “behind” is most decidedly not good for my morale. Timeblocking and scheduling are great, but they require discipline. I like to think that I am effectively entering into a short-term contract with myself. If the terms aren’t clear, the chances of failure go up (significantly). Interestingly, I think this scenario represents a conflict of interest: I am basically the party responsible for monitoring that contract, as well as the one actually executing the work.
Besides having a clear plan (a statement of work) I think the next biggest concern involves distractions. In my experience, you can’t get rid of distractions, but you can be judicious about what distractions you choose to entertain. That gets to the same end-goal of choosing when to focus on distractions, but puts a different emphasis on the problem.
The “hard” part (to me) is that developing the intuition of what to do (and when) is much easier said than done. Maybe because it is a constantly moving target?