I have heard conflicting opinions regarding this matter. Its really not that big of a deal with prop, I think the half life is long enough to be shot eod. I actually prefer doing both ed, but thats just me.
I think for the majority of people the difference in blood concentrations is miniscule and should not matter. I could see if you were a pro and trying to squeeze out every ounce of muscle but for the average juicer EOD seems fine and just less injections
It may not make a lot of difference clinically (end results), but pharmacokinetically, levels will be steadier w/ ED.
I do prop/fina ED, I use half the dose I would for an EOD dose; therefore, the peaks and valleys will be of lower magnitude, which I like. Peaks and valleys often contribute to sides that might be avoidable with more consistent blood levels.
My $0.02 worth.