From my notes, copied from various places...
1)
Following a workout:
1-5 days - Fatigue
5-8 days - Starting adaption
8 days - 3 weeks - Adapted
Over 3 weeks - Losing adaptation
2)
Intervals — take 8-10 days to fully recover (hardest on the body of all types). In training, allow 5+ days before the next one. Do easy run the day before and day after
Tempo run — takes less time to recover. In training, allow 4 days before the next one. Allow 8 days before goal race. Do easy run/speedwork the day before and easy/speedwork/long run the day after
Speedwork — depends on length/intensity, e.g. 400s are more like intervals. In training allow 2-3 days before the next one. Do easy/tempo/long run the day before and easy/long/tempo the day after
Long run — takes 4+ days for full recovery. Do easy run/speedwork the day before and easy run the day after
3)
Workout type - intensity - time to see benefits
Speedwork - Hard or Medium - 1-3 days
VO2 max/Hills - Hard - 12-15 days
VO2 max/Hills - Medium - 9-11 days
Threshold - Hard - 10-12 days
Threshold - Medium - 7-10 days
Long Run - Hard or Medium - 4-6 weeks