Everyone is different. Some people can focus better, some can't. It also depends on the weed.

Personally I can learn on weed but it's harder. I do better without. Most people retain more sober. I would worry about the real issues that make my life so messed up that I need so many drugs to cope rather than worry about which combination will make me feel better. That shit all has a root.

We are the culmination of our experiences and choices. Depression, anxiety and mental disturbance are treated as diseases when really they are the symptom.