Once a week, a run should be long enough to consist of 20-25% of your total weekly volume. If you are running a total of 300 min for 6 days training week, the Long Run should be about 60 min that week (20% of 300 is 60). That means your other 5 days should be around 45-50 min each run. If your total minutes are around 500 min for 6 days, then the long run should be around 1:45 – 2hr run or 100-120 min (20-25% of 500min) leaving 380-400 minutes for 5 days or about 75 – 80 min runs each day.