Originally Posted by DeepGreenLawn
And a vibrant healthy lawn will control 99% of the lawn. However, I have a customer with the thickest, most beautiful lawn you have seen and I still hand pull about 10 weeds per trip in an area of about 6k sq ft that some how make it through. If they can make it through this lawn, they can make it through any lawn. So... there will always be weeds... just a lot less.
Over time, the weed seed bank will be depleted providing you don't have a source of weed seeds building it back up. It doesn't hurt to look around to see where potential inputs into that weed seed bank may be coming from and to deal with the source directly if possible.