The evidence I've seen suggests 2 over 1. It seems like sustained (not intermittent) exposure to diverse things that don't make you sick is good for the immune

The evidence I've seen suggests 2 over 1. It seems like sustained (not intermittent) exposure to diverse things that don't make you sick is good for the immune system, while actually getting sick has no benefit and is actually detrimental, beyond limited immunity to the single strain of the single thing you got infected with (and even that isn't guaranteed).