After reading this thread:
I got curious. So I tried alternating between the big ring and the small ring for each set of intervals. It was quite educational! I found the big ring to be mentally much easier because it required much less concentration on keeping a smooth pedal stroke and required less core stabilization for the same power output when compared to the small ring. The small ring on the other hand really exposed how ugly (i.e. inefficient) my pedaling would become when fatigued or when trying to put out the big watts.