On Day 1, I go out and do 3 - 4 hrs with lots of climbing, and am pretty whipped when I finish.

Now, let me give you two scenarios for the following days:

Day 2: Go back out and ride more hills, hard, until I crack (legs fail). Say 60 - 90 mins.
Day 3: Recover
Day 4: Continue with hard training

- or-

Day 2: Recover
Day 3: Continue with hard training


In other words, is there any significant training benefit from the first scenario?