To the OP, I've tried mixing in some protein with my orange sports drink during long rides -- it tastes wonderful, like one of those chocolate oranges, and I figure it's not doing me any harm. I just don't know if it confers any benefit.
The basis of my comments lay in an understanding of the nature of exercise with respect to the real-world situations encountered by ultra-cyclists or Ironmen -
during competitions.
That is why I see no point in discouraging protein consumption during everyday workouts (or rides), nor do I see my perspective as "right or wrong" with respect to what types of results are found in laboratory studies.
The bottom line, immediate energy needs are served best by carbohydrate. The "time-lines" for when protein becomes valuable to regeneration of other muscle-supporting organ systems, are as infinite as all the combination of all training programs and all race/ride situations.
I just don't think in terms of "micro-cycle" training/rest periods -and I said so. If you are going really hard, save your protein until when you "back off." (or are resting completely)