My question about stoichiometry method being used by an instructor/s

(Intro)
At exam in country where I live it's required to use notations such as: n(element), c(mixture), V(H2), etc just to keep track what's happening.

(About method used) 
When I watch chemistry guide videos, the instructor always write stoichiometric equation without the notations I mentioned above which always confusing me what formula is being applied I know they mention "a grams of X/ b g/mol of Z" the conversion of units is the most confusing part because they skip at least 2, 3 notations and go straight to answer.

(Question)
Is this method common in education or it's just how an instructor used to do stoichiometry?