Where overhead watering can be a problem is with fungal diseases that require a wet leaf before they can infect a plant. To give an example, daylily rust spores cannot germinate to infect a leaf unless that leaf has water on it for several hours. So if you want, or prefer, to water overhead then do it early morning - the plants are often already wet from dew, and the leaves will soon dry quickly with the sun. That reduces the number of hours the leaves are wet. Watering late in the day would be the worst time. The leaves will potentially not get dry until the next morning. You can totally cover a daylily leaf with rust spores but if you can keep it dry it will not get rust. Of course that's impossible outdoors but in a house the leaves would have to be misted to provide wet leaves for long enough to enable spore germination.
A downside to using fungicides is that they can increase pest problems by killing the fungal diseases that attack and kill the pest, so the fungal problem would have to outweigh the potential for pest problems. Also, going back to leaf streak, that fungus infects via wounds (unlike daylily rust which enters through stomata), so can be related to pest or weather damage.
