Long runs/weekly mileage

Unpopular opinion it seems but having done a few 12 hrs and 1 24 hour along with a few 50s. Long weekly mileage doesn’t work as well for me as normal weekly with long 20 mile runs on weekends and back to back 20s or 30/20 at peak week. If i do 60-70 mile weeks with no super long runs my legs still start to wear around 14-16 miles. Consistent weeks of 45-50 but with long weekends and i can get past a marathon without any real breakdown. Endurance is always much better. Anyone else similar?