Yesterday's thread on the 2 x 20 intervals got me to thinking?? Is there a big difference in doing 2 x 20 at a certain watts(say 250) vs doing 4 x 12 at the same 250 watts? Or should the 4 x 12 be done at a little higher wattage?? If you're within 8 weeks of you A race(1/2 IM), which would be more appropriate to do??

Thanks