The 10K race is a slower, more comfortable running pace than the 5,000 meters. Running 8 to 12 seconds per mile slower makes the 10K distance a joy. You can rectify mistakes. Compared to after running the marathon, 10K running hurts less afterwards. Your walking can entertain friends for days after running a marathon.
Most runners can t race many marathons.
10-20 marathons per decade is most runners limit. 15 miles is your long run. Here is a summary of 31 minute 10K runner David Holt's five training phases. Mileage Base Running for Aerobic Endurance. Low level aerobic exercise is the safest way to build aerobic endurance for running.