If they were applying in those conditions I can only assume it was for the money and not overall health of the lawn.
I'm in NC and I stop applying on fescue during the hot weather June-August. Only apply fungicides for brown patch. When it's in the 90s all the time I don't take the chance of burning the lawn. I state that upfront in my program. I have thought about milorganite or other organic around May, but experts say not to apply fert in the heat.
My warm season gets apps during the summer for fert and thanks to celcius I don't worry about the heat. Still keep an eye on rain though. Many summers I have to stop or delay a round until some good rain arrives.