On the Linus point, I'd bet there were countless months where he was bringing ideas together in his head and planning how he'd do it before actually finding the time to sit down and write it.
It would be interesting to know whether he had devised some kind of project plan ahead of time. But I suspect not. I'm sure he had been thinking about the technical details of what he wanted to build - which yep, we all like to do that! - but I doubt he bothered to break down a set of approximately-ordered 1- to 3-day work units, which is what many of us struggle to be good at.
But for me it's very easy to overdo it. Give me interesting chunks of about a week or two, with a tight deadline, and I'll do my best work.
Remember, Linus wrote Git in two weeks. And there was no project manager in sight.