Answer: If your grass is being scalped, meaning more than one-third of the leaf blade is being removed when it is mowed, it can kill the grass. It's probably not the technique but more that it's not being mowed often enough. When grass is actively growing, it sometimes needs to be mowed twice a week in your area. If it looks scalped after being mowed, ask that it be mowed higher or more often.
Another consideration - If your lawn is more than 3 years old, native grasses may appear in your turf. They show up when other grasses die out and for the most part they are cool season grasses. This would account for their browning out in the summertime. The lawn will green up again in the fall when the weather cools. Or, you can overseed your lawn with perennial rye to green it up now. Simply broadcast seed over the entire lawn. Or you can rake out the brown areas, removing dead grass and grass roots and overseed just the brown areas.
Best wishes with your landscape!
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