I've spent 20 years trying to decide what I could have done differently. Usually I conclude that I should have taken out loans. In my defense, I was 16, knew nothing about loans, thought they were scary, and had nobody to advise me otherwise. My single mother was working full-time to support two other kids, and didn't have the bandwidth to help me with school. Besides, that was back in the days before student loans became the foregone conclusion they are now. It only just now occurred to me that I could have blown off the homework, and graduated with lower grades, but there is no way 16-year-old me would ever have considered not doing homework.
Yeah, you're right on the time management part for sure. I was the most efficient with my time during that period of my life than I've ever been. Basically work, class, study in library, repeat. It's not that bad, people are capable of more if they choose to. Best time of my life. It doesn't get better for sure. I've worked like a slave since then, with zero intellectual stimulation as I had at school other than what I seek out on sites like HN.