I graduated with a degree in Mathematical Sciences and spent near all of my final year vaked. I learned a bit of material and also realized which direction I wanted to go with my thesis whilst stoned (chose something concerning fractals, google it if unaware, at the very least there's some amazing pictures).
Learning new concepts stoned took quite a lot longer as you tend to attack the problem from ALL the angles, too many angles! Pursuing any problem from so many angles may be more time-consuming but it's certainly more thorough. I felt like I'd mastered the few concepts I learned when vaked.
However, I inevitably left the study until last two weeks and needed every waking second to be properly utilized so I didn't get to vape whilst stoned when it mattered.
I think I'd need to be more interested in the subject for that to work. It would have to be something I'm passionate about. Maths is fine, but there's few in the world who consider it fun. If you think you're part of the few, then YouTube some linear algebra and just grab onto the edge of your seats!
On the other hand, I'd say there's not many uninteresting subjects if you're stoned enough! Just comes down to willpower then
