The if the probabilities of catching COVID on two occasions are x and y, the the probability of catching it at least once is 1 - (1 - x)(1 - y) which equals x + y—xy. So if x and y are large enough for xy to be significant, then splitting is better because even though catching it the second time will increase your viral load, it’s not going to make it twice as bad as it already was.
The if the probabilities of catching COVID on two occasions are x and y, the the probability of catching it at least once is 1 - (1 - x)(1 - y) which equals x + y—xy. So if x and y are large enough for xy to be significant, then splitting is better because even though catching it the second time will increase your viral load, it’s not going to make it twice as bad as it already was.