I used to always start by double digging my beds, then adding tons of organic matter, maybe finished compost, maybe just leaves and grass clippings. but lots of it. It still took two years of adding stuff pretty heavily before I could tell the soil was actually changing the way I had expected it to in a month or so. It just takes nature a lot of time to improve the soil, sure the clay was much more porous but it still looked like and acted like clay, after a couple of years I could actually see soil improvement, still a lot of my deeper clay still looks like clay. I don't know how many years it would take just by putting stuff on top. But that is all I do now, unless I am starting a new bed, just keep adding stuff on top and letting it decay, it forms a thin layer of very fertile looking very soft viable soil when the worms work it over a period of time. But when first starting out, I had no worms.
