My understanding is that reducing the amount of virus particles you are exposed to means the virus takes longer to ramp up and gives your immune system more time to come online, but I don't know how true that is.

Also, immunity to Covid is very complicated. It has a lot of properties that directly attack or evade the immune system. Moreover, it is evolving rapidly and dramatically, with new strains emerging every few months that are distinct enough from the old strains that infection with the old strain does not confer significant immunity to the new strain.