I'll be curious to hear how things are going.
As far as I can remember, this is my first time hearing about aerating ground plants at all. Soil that has been gardened for any length of time by having organic matter added occasionally and repeatedly should have all of the oxygen a plant needs. Potted plants get a lot of publicity for needing airy soil, but that is not the topic of discussion.
I've really only heard of aeration in regard to lawns. There is a roller thing with spikes and it is walked around the lawn to aerate it. I think it's a busy-body thing that people who get paid to tend lawns invented so they can charge for doing more things to the lawn, but my opinion is clouded by my disdain for the growing of grass merely to grow grass.
Aeration (using to mean presence of oxygen and decent drainage) occurs at a microscopic level, not by digging tons of little holes in the ground or, as said, scratching the surface. Without a layer of organic matter on the soil surface, the soil will dry more quickly than necessary, compact, and when it rains, the water will flow across and pool instead of soaking in instantly.
There should be dedicated places for stepping and an effort to never step anywhere else. I use 12" square bricks for stepping stones. They're inexpensive and just the right amount of space for 2 feet. I always pick up a few when I'm where they sell them, eventually I'll have paths. I can move them as needed, also handy for smothering a tough weed that didn't come all the way up when pulled.
Although I'm speaking from the experience of watching this transformation happen in various places, don't just take my word for it. Dr. Elaine explains it so well, without a lot of technical jargon. Just pure plant happiness info.
https://m.facebook.com/jamrege...
The answers so far seem to indicate that the answer to the original question about how often this is necessary is never.