From my own struggle to learn something each day I can tell you that - at least for me - what you said is wrong. There are many "workflows" I tried and am still using, but generally speaking even 15 minutes is enough to gain something valuable. For example, when reading a technical book 15 minutes is enough to read a descriptions of a (sub)problem and to understand high-level concepts used in it's solution (if it's not, you're reading wrong book). I then go to work and think about the details of the solution during the lunch break and commute. Another 15-30 minutes in the evening is enough to check what I thought up with a book and realize where my thinking was incorrect. Then the next day I can code up whatever I was reading about in an hour max, but frequently less (if not, then I was reading wrong book - that is one which I was not prepared to read yet). Then in the next days I can deepen my understanding with 30-45 minutes sessions, and at the end of the week I have the problem internalized and I can move on.
That being said, when I'm not under extreme time constraints, I'm using other approaches. For example, for a whole week I'm reading and gathering bits of information I will need to build something. I have a large file, where I paste links, paragraphs of text from articles and write tiny little snippets of code, either mine or borrowed from somewhere. All this takes an hour or a little more each day (but it's nice that it can be divided into pieces). Then over the weekend I try to make this amorphous mass of data into understanding, in one or a few coding sessions.
There are other ways to make the best use of what little time we get, too. They'd better be, because otherwise we'd be royally screwed as working programmers :)