You're clearly not a student :). I'd love to choose when to go to bed, but that's not really compatible with a workload challenging enough to appease admissions counselors.
Use time-boxing as a scheduling mechanism. If you find you have more work to do than time to do it, start lopping off items from your to-do list, and/or identifying how you can accomplish a sufficient effort in the time available.
That is likely to be a far more useful life lesson than whatever subject it is you're studying at the moment.
You also have to learn how to schedule downtime. People cannot run 100% 24/7/365, and attempting to do this is at best very painful, and at worst, literally, suicidal.
If you want a little more unorthodox advice I'd offer, "don't buy the textbook unless either (a) it is a workbook which must be submitted for the grade or (b) you were really so powerfully impressed that you want this book as a lifelong reference." Ask the professor to ask the library to put the textbook on reserve in the library -- so that nobody in the course can take it out, but rather you share it at the library. If this leaves you muttering about Kant's categorical imperative, remember that if someone else is using it, you can form an impromptu study group and make a new friend. :D. For that matter, student societies should have copies of the texts, and a study lounge at the department might also have them. If nothing else works, copy homework problems from a friend taking the same course and look up the same material in alternative texts in the library (or on the Internet) -- but that's almost never necessary.
Don't expect life to get easier. More rewarding, IMO, but not easier.
My dad is an accountant. He gets to work at 7:30am and gets home at 4:30pm. He spends about as many hours at work as I do at school, but when he logs off for the day, he's done. I can't remember the last time I actually completed my obligations for the day. If you do manage to do a good job on all the problem sets and readings before losing consciousness, there's always a test to be studying for or a paper to be revising. I procrastinate because there is literally no such thing as "after homework is done."
I don't mean to complain - I gave myself this courseload and I've done well enough with it that I'll be going to my dream school next year (UChicago - yes, I know, the workload will increase exponentially). Sleep deprivation is a price I chose to pay. But I do think that most professionals have a day which ends - usually before 7pm, but at some point it ends - and several hours to commit to a social life, family, side projects, pleasure reading etc. as they please. Obviously not in 80hr/week fields like law and not in startups about to ship, but on balance. Is this not accurate?
There are a lot of great, lucrative careers that give you a clear boundary between work and home. Some of these are that way by nature, but really all can be. There are niches even in law and medicine, that provide for a if not 40 hour work week, something close to that. These often will be the jobs that pay the below-median salary in that field.
But anything that resembles entrepreneurship is going to feel a lot more like what you are doing now than what you see in your dads career. (Also worth noting on the subject of your dad that you presumably didn't see him when he was starting his career.) Sure, what I said in the previous graf applies to entrepreneurship as well, but... the disposition that drives a strong work/life balance seems often orthogonal to the ambition that leads you to working for yourself to begin with.
So if that life interests you -- if building and growing something is your destiny -- then my POV here is to know that everything you wrote about your current life, the "last time I completed", the "always a next thing to do", the "no such thing as done", all of that applies wholly to entrepreneurship.
Of course, like I mentioned a couple days ago, it can be tremendously rewarding.
I'm only 30, I have a lot to figure out still, so take all that with more than a grain of salt.