The older I get the more I believe there's no one correct answer for any single question, that everyone who claims knowing the only right answer is a crook.
One of the things I keep hearing people give lectures about is the importance of "Focusing on one thing at a time". Every time I failed at something when I was young my parents and teachers used to blame me for trying to focus on too many things at the same time. They thought I was distracting myself by trying to solve some math problems, then some social studies, and then back to math, etc...
I've been doing this since early age, and I still do that now as a web developer. I hate working on a single task for so long. I prefer switching between multiple projects rather than working on one single project for a long time.
That's just the way that works for me, jumping between tasks and working on multiple products in the same work session. I find myself more productive that way, otherwise I get bored and feel stressed.
The point is, it's not bad to consider what those productivity gurus have to say, but know that you are the only person who knows how to become more productive.