I've recently started work on a large translation project (about which more in due course). This sees me grappling with the Arabic text for several hours each day. Early on, I tried replicating my '4 perfect hours' approach that had worked so well when writing my PhD dissertation.
Translation is hard work, and tougher on the brain in ways I hadn't first anticipated, not having done it full time before. So I've found myself adjusting my 45-minutes-work, 15-minutes-rest cycle to something closer to 25-minutes-work, 5-minutes-rest (with a longer 15-20 minute gap every 4 cycles).
For writing and anything where you're trying to hold lots of pieces of information in your head, it makes sense to go for longer stretches of time if you can. 45 minutes was ideal for writing my PhD, since any shorter and I felt like I was loosing too much time rebooting all the information at the beginning of each new session.
Translation is far more piecemeal, in a way. I can work on one sentence at a time, at least in this stage of the process, so shorter sessions work just fine.
This is all just an extended way of saying that customisation is important, and whatever you read online (or hear on a podcast or whatever) needs to fit into your own life, needs and patterns rather than the other way round.