For the sake of future readers... best I can tell, my heavily compacted soil can be aerated AT MOST twice a year. Once it's in better shape, though, I'll need to take it down to once a year.

I'm going to spend the summer trying to dethatch the lawn, then thinly spreading compost to encourage earthworms to mess around in these compacted areas. They should help to aerate the soil naturally.

Yes worms will help to develop the soil structure. So do the beneficial fungi living in the soil. I aerated my lawn in San Antonio one time and saw no change in it. I was trying everything I could to make it better. Chemical fertilizer seemed to have stopped doing anything. Then in 2002 I tried using corn meal as a fertilizer, and the lawn turned around.

When you core aerate you punch a lot of holes and somehow those holes are supposed to cause the soil to become less compacted. I cannot explain the logic. In the late 2000s I was using a soaker hose to soften my soil. It worked perfectly, but it took weeks to soak in along one strip of hose. On another forum I learned they were using surfactants made from industrial soap ingredients. I decided to use shampoo, and it worked great! In 2012 I applied baby shampoo at a rate of 3 ounces per 1,000 square feet and watered it in. The only explanation that makes sense to me is the shampoo allows water to penetrate more deeply into the soil which creates a more hospitable environment for the beneficial microbes. Together those 10s of thousands of species of microbes create a complete soil structure of air passages which allow water and air to penetrate as necessary. We moved away in 2015 and the the soil was still benefiting from the shampoo years earlier. Every time it rained the soil would become so soft it was a little uneasy to walk on it.