I have never used the 5 day, though I have seriously considered it on some show heifers. In research studies, the 5-Day has a slightly higher conception rate, in my opinion the advantage is pretty insignificant though. So for me I just call it pretty straight up, and as you said the 5-Day requires an extra shot in there, which isnt only more work(especially when you have to pen cows and work them in order to give that shot) but it is also more expense. So for us we have just always chosen to do the 7 Day protocal.