Individual plant sheet mulching

Hello all. I had an idea this year for a new type of sheet mulching that is for individual plants, not for large areas.
I chose the most difficult spot in my yard to give it a test run. An area where crab and Bermuda grass take over every summer. It has also never been work, or fertilized in anyway.
I started off by choosing the original planting spot then measuring three feet (one meter) away for the next plant. I figured that would give me plenty of space to get my mower between plants. After all, it is still yard.
I chose peppers simply because there were so many ready to plant. After digging twelve holes I put the new starts in and went to work cutting twelve inch pieces of cardboard. A small hole went into the middle to place the new starts in.
The peppers grew great but four weeks later the cardboard had been overtaken by the weed grasses. At that point I cut larger pieces of cardboard and placed over the original ones. That was pretty much all I did this season. The pepper yields were great and equaled what I received from cover cropped gardens. I’ve started removing the spent plants and cardboard and letting it return to yard until next spring.

I did something like that two years ago and stuck pumpkins and sunflowers in the holes in the cardboard. It worked really well and I didn't really water them once they were established.