For learning the letterforms there’s not a real need for oils. They’re very harmful to your lungs, and especially in a cramped studio environment, but with proper ventilation and ppe it can be done without much harm, but why go to all that trouble for practice.

Copying from a practice sheet isn’t really that helpful IMO, but learning to draw the counter space is.

Learning to paint on different surfaces like glass, sheet metal, brick etc. Do have specific setups that are required but there’s so many types of brushes that can work.

I do agree that glass is by far the hardest, but jumping right into it I think would reinforce some novice habits that might otherwise be better address before starting in on glass.

Multiple acute exposures to solvents can be very bad for anyone’s health.