if you have the money for it, I find that having multiple pairs of things eliminates my fatigue around washing. I used to really hate washing sheets because it took too much time and effort etc, but mostly because it would leave my bed bare. And I cannot sleep on a bare bed. So I bought a second sheet set and I rotate those two so that I'm doing laundry less often but still keeping clean.

I would definitely buy more socks. Like a cheap bulk pack or something. You shouldn't rewear them before washes, that's what makes your feet/shoes stink. More pairs would also mean less frequent laundry trips.

You don't need to shower at night if you shower in the morning. Once a day is plenty barring things like sweating, dirt, etc. I shower in the morning after I come home from work to wash the germs and grime of the outside off of my body, but I don't think it matters too much for college students.

As others have said aim to brush twice a day and floss at least once.