I have lived at my current property for nearly 7 years now, and while I cut the main area up against the house once a week, I typically let the rest grow out for a month. Never used sprays other than flea and tick for my dog’s yard, and never even pulled weeds.
Still, it’s almost all completely homogenous grass. Not sure what species, but it doesn’t grow very high. 3-5 inches. No wildflowers have encroached, no other grasses except clover, not even weeds other than dandelion. The only other thing that grows anywhere is some English ivy that’s pissing me off all over the house. Every time I pull some out and dig up the root, I find more a few days later.
Still, MUCH higher insect, pollinator, and other wildlife activity vs my previous residence. It’s been nice seeing fireflies again, even if it’s still nowhere near what it was when I was a kid.