Treat your limited energy as information the plan should include.

Energy gets treated as a moral variable, something you ought to be able to summon if you cared enough. It behaves more like weather or money: it varies, it can be roughly forecast, and a plan that ignores it fails on contact. Building around the energy you actually have is not lowering the standard. It is planning with a real input rather than an imagined one.

Find when in the day and week you reliably have something, and put the demanding work there. Leave the low stretches for tasks that survive being done badly.