Leaking tire plug repair

I lived on 4 miles gravel road for over 30 years. I would have anywhere from 10 plus plugs in each tire . Some I would have to double up the plugs to stop the leak. Sometimes would have to replace plugs with new plugs. Tire shop would want $20 + to patch not to mention the down time to get one fixed. That's over $800 for a set of 4 tire patches, if they would even patch one that many times. 10 + plugs average 4 years of driving 50 miles to work at 75 -80 never an issue. Plug and replug and drive on !