How to avoid brown patches on lawn?

A dog run

If it's not your dogs then it's grubs.

https://www.houselogic.com/by-room/yard-patio/brown-grass/

Are the sprinklers, perhaps, not hitting those areas and thus, they are dry all the time? I found we needed our sprinkler heads re-directed from time to time so all areas of the garden got enough watering. We also set the timer to water for a longer period of time.

Depends on what is making the brown spots...could be grub worms or another insect issue, could be dogs peeing on the grass, could be a bacterial issue in your lawn. Dig around in one of the brown spots to see if you find insects, etc. Ask at a local garden center if there are bacterial or fungus issues in your area.