yes after the first few intervals i was having trouble maintaining a high power level. I was more concerned with keeping the watts as high as i could rather then steady. This is where I have a problem determining effort. When I see "all out effort" I think "go as hard as I can and try to last a whole minute" even if it means spiking output instead of steady. Obviously I could be destroying myself too soon to be able to finish the whole interval but I have a hard time otherwise determining if I am going hard enough.
Whenever I manage to keep a steady pace I always feel like I must not have went hard enough.