in a way, it's probably better to think of a recovery day as something you take before a hard training day.

the idea is that you should be able to get the maximum benefit out of each workout. for example, if i did hill repeats on thursday and wore myself out, and then tried to do max effort intervals on friday, i would not be fully recovered and my friday workout would benefit me less.

however, if i moved my hill repeat day to wednesday, did a recovery spin on thursday, and then my intervals on friday - i would be much stronger on friday and benefit more.

i tend to have a recovery ride or an easier endurance ride before the most important workout of the week.