(meta: I'm not sure if I should make a Discussion post for this, so I'm posting here. Feedback most welcome)

I'm exploring the following hypothesis : sometimes, you have to give up constructive actions for the sake of focus.

Most productivity methods suggest the obvious, to keep wasteful activities in check. It could be gaming, chatting, checking news websites. They all share a common trait: you don't gain any significant utility (nor money, nor fun, nor rest) for spending more time on it. You achieve the same result by spending a little time on it, rather than a full day.

With productive activites, time spent and value created aren't proportional. Sometimes you're lacking energy, inspiration, and it's okay: you don't have to work yourself ragged.

If you have multiple tasks to be achieved in parallel, you should treat them as sequential anyway. Focusing on one task at a time yields better results than task switching all the time.

Problems arise when you find inspiration, or a sudden peak of interest for a certain task which is, useful in isolation, but which doesn't fit in your schedule. Maybe a discussion with a friend sparked the idea of a story to write. Maybe you're considering moving some furniture because you're well-rested and full of energy.

Even if you could be maximally productive for a given useful task, you should treat it as a wasteful activity if you have something else you planned to do. If the idea sounds good, write it down. If it's really good, hype will come back another time. If you're energetic, do the most physical thing you had planned to do. Energy will come back another time.

The goal is not to add another task on your current schedule and mess with the plan you've set for the day, like you'd do with "classical" wasteful activities. You can convince yourself easily that news websites can wait another day. The unintuitive part is this also holds with most productive activities, even though you're training yourself to not defer work!