Is attendinag all classes necessary?

mam i have taken online classes for cat, i am in my 3rd year b.tech right now, i have a good maths background

my doubt is should i attend all classes(especially quant) as it is a little hard to manage all classe and my engineering study, b'cuz i am able to read from the modules and then solve effectively, so i was thinking to attend classes for varc and lrdi only and do rest myself, and if i get a doubt then just watch lecture for that topic

plss help