so 2 masks is better than 1 but 3 is worse than 2... how are we sure 2 is the optimal number? surely, calculus must be done to determine the optimal fractional

so 2 masks is better than 1 but 3 is worse than 2... how are we sure 2 is the optimal number? surely, calculus must be done to determine the optimal fractional number of masks between 2 and 3. (my money's on Euler's number.)