It's interesting to read the original post, your comment, and the responses to your comment. There are many different uses of the word "focus" and its relationship with saving time.
For me, focus is simply about depth over breadth.
If you want to do high quality work and enjoy it, you need to clear up your schedule to give a particular endeavor the time it deserves and then some. You do this by shrinking the scope of what you're working on down to something manageable, something you can do a stellar job on in the time allotted. That requires saying no to everything else, even things that are promising. You can get to those later.
If you want to do mediocre work, then take on huge projects with a ton of responsibilities, and try to work on them all simultaneously. Not only will the quality of your output suffer, but as an added bonus, you'll earn a packed calendar.
For me, focus is simply about depth over breadth.
If you want to do high quality work and enjoy it, you need to clear up your schedule to give a particular endeavor the time it deserves and then some. You do this by shrinking the scope of what you're working on down to something manageable, something you can do a stellar job on in the time allotted. That requires saying no to everything else, even things that are promising. You can get to those later.
If you want to do mediocre work, then take on huge projects with a ton of responsibilities, and try to work on them all simultaneously. Not only will the quality of your output suffer, but as an added bonus, you'll earn a packed calendar.