yardwork really chaps my hide, ya know
recently bought a house and the previous owners obviously didn't give a crap about their lawn, so it is completely overtaken with weeds. been working on trying to salvage it for over a year, and am about to just give up and till the whole thing and start over.
If the lawn is in really bad shape, it can take quite a while to bring back. Most people don't have the patience or just aren't willing to put in the work.
I would suggest applying a pre-emergent herbicide in the spring, a couple of weeks before weeds start appearing. Then, maintain a fertilizing & post-emergent herbicide schedule throughout the spring/summer/fall. Then do some overseeding later into the fall. Of course, you should be watering your lawn regularly as well. Repeat this process for a couple of years and you'll see good results.
If you don't feel like waiting that long and have the cash, tear it all out and put in sod. Then stick to your schedule so you don't lose it all to weeds.
If you tear it all out and simply reseed, you're still looking at a couple of years before you have a decently established lawn.
Anyway you slice it, keeping a nice lawn is a lot of work. That's why you don't see very many of them.