Something new just popped up my brain regarding this. My Year 12 teachers have been like 'gotta prepare you for uni', and so have mostly neglected to set homework. I'm left to basically spend a bit of time contemplating what to do, which slows my progress down. I'm the kind of person who wants to ride the academic momentum from school and transfer it to my studying.
Yeah, so it's about doing what's most important, since required tasks are essentially non-existent outside of formal assessments. I know I can't do absolutely everything, but is there anything I can do to make the set work less overwhelming?
Also, I suck at studying on non-school days. Just thinking about having to study makes me wince and moan in pain (maybe slightly exaggerated, but it doesn't fill me with joy). How can I make studying not-so-laborious on weekends and those kinds of days where there are unfortunately no classes?
I'm in my 3rd year of uni and still not properly comfortable being fully independent in directing my study! It's a really common thing that I think almost everyone struggles with. Being fully responsible for what you do is empowering, but also a bit terrifying haha.
If you're trying to prioritise study that isn't for assessments, I'd say reflect on what you've done that day/week at school and ask yourself what the key things were that you did in each lesson and what you want to take away from them. If you've got a syllabus/study guide/learning objectives, use that as well. Maybe also try and write down something you think you did well in class (i.e. understanding a concept, etc.) and something you need to work on (perhaps you made mistakes on one sort of question, or there was something you didn't understand, etc.) to help figure out what you do and don't need to do.
Re: studying on non-school days. I was awful at this in HS and am still pretty bad at it in uni! For me, it's about changing my environment. I might go to the library, go to my boyfriend's place or something similar. You can also try staying back at school a bit later on school days (or coming earlier) to do your set work or things you want to do so that you don't really have to do much on weekends (I did this in HS) - there's no rule that says you have to study every single day of the week (and I think it would be unwise if you did!), you can always save weekends for leisure and catching up with friends.
Kind of off on a tangent, but I think working on self-talk is also a really important thing. You said you feel guilty when you don't complete all your tasks. When you get that thought, try and balance it out with something positive - so you have the "there's so much I didn't get done" thought counter-balanced by the "yeah, but I achieved a solid base and got the key things finished" thought. Being kind to yourself is such a massive thing - not just in school but throughout life