Unless they are new lawns, they don't need watering morning or evening. As soon as the rain comes the lawn will quickly recover and not having to mow in this hot weather is a bonus, surely?
Lewin, nematodes. Buy off amazon or the garden centre.
John Herbert, watch where the dog wees and then water the patch with a watering can, keep then dog well watered overnight, concentrated urine first thing in the morning is worst, or train the dog to wee in one place.
Repairing the lawn is easy, just rake the affected spots and reseed.
I have been giving our dog slices of tomatoes for a number of years now and it certainly has reduced the number of scorches though she doesn't get them every day and maybe that is the reason the problem hasn't gone completely. I did notice this spring, when the grass started to grow, that scorches appeared more frequently and wonder if there is some chemical that the grass produces during growth that reacts with the urine. Any ideas? I like the tomato sauce idea and will give that a try.