Famous Thomas Jefferson quote: “Never put off till tomorrow what you can do today.”
I used to try for that. Squeeze another practice session in, another experiment.
For non-magickal work, where you sleep a full night and wake up rested, it’s probably good advice.
But magick takes more out of you, especially if you’re learning new skills using new mental muscles. After a few days doing as much as I possibly can, I slow down noticeably. If I keep pushing, I shut down and have to rest.
I never took rigorous data on it. There’s so much natural variation in how much I can accomplish any one day, that the data would be hard to use anyway. But I’m pretty sure I accomplish more by working until I’m tired, but not exhausted, so that I’m fully recovered each morning.
One exception to this: If you’re going to be caught up in something non-magickal for a while, like a work project, you can exhaust yourself the day before, then use the work time to recover magickally. You won’t be as sharp for the work project, though, so up to you if it’s a good tradeoff.