When lawns are damaged by insects and need to be repaired. We almost always recommend aeration and overseed as the method to be used to get the lawn back in shape. The seeds falling in the aeration holes are almost sure of germinating. Here is a photo of an core aeration hole on lawn that was aerated and seeded.
The Photo was taken 7 days after the aeration was done. (now this may be an exception in how fast the seed will germinate. The amount of water the seed receives will determine how fast it germinates. So watering and rainfall will affect this)
Seeding is much less expensive than sodding. Sodding is great if you need an instant fix. Seeding takes a little longer but in the long run is a better fix. With seeding, you will normally use a seed mix with several species and varieties. This variability in the lawn population will increase the lawn's resistance to disease and help it to overcome those conditions such as soil, light/shade, and drainage.
Aeration/overseed is much more economical than topdressing and seeding. Topdressing is also great for the lawn, but when it purpose is to repair the lawn, aeration/overseed is the way to go. There is not the same amount of labour needed to move wheelbarrows of soil to the furthest corner of the lawn.
Sometimes, people are concerned that the holes are 4-10 inches apart. With aeration/overseed, you are unlikely to see a whole lot of green "fuzz" of seeds coming up. That green fuzz of seeds germinating is what one often sees when topdressing and seeding.
One thing to remember is that we only need one grass seedling every 6-8 inches to germinate.
In the situations where a fuzz of grass seedlings grow, one must remember that if there are a hundred seeds in a small area the size of a sheet of paper, only 2-4 seeds are likely to survive. I know that because I have seen a hundred weeds seeds grow in a small area much like the grass. A few weeks later, when I didn't pull out those weeds, I notice that even though there were originally a lot of seedlings, only a have dozen have survived. The rest of the seedlings have died out due to the competition from there "litter mates."
The same thing will happen with the grass seedlings. It's just that with grasses, it is much harder to distinguish individual plants.
After the aeration/overseeding, the lawn should be watered daily to allow the grass seed to germinate.
Turf King Hamilton Halton Haldimand