Yeah, 'the body cleansing alcohol is able to clean out MC impurities out of his body so his potential expands that is one of the reasons for MC fast growths, as for 'Vitality Injection' it does nothing but fill body with vitality so even if MC is tired he won't feel nothing and would continue his training at frightening speed. But MC would feel fatigue as soon he Vitality Injection ends up. I even mentioned that in starting chs.
then there is also the MC technique, Max doesn't choose the flashy techniques, he chose what is best for his body and that is also the reason for Max growth.
The main novel is about to be completed in the next 200 chs, I was just focused on this novel to build momentum. I'm not dropping my main novel you will get 2 chs in a few hours