Due to half-lives and things like that the ED schedule isn't necessary but it's been shown in some cases to help control aromatase in some cases by applying more frequent injections in smaller doses. This is one of a few reasons some guys will inject large ester testosterones daily in smaller doses when they're using a total large weekly dose. If it really makes a difference I'm not sure, but I've read a few theories that make sense.

The Letro/Gyno thing you mentioned, Letro can reverse gyno symptoms in the early stages....when they first appear but it's not going to do anything to reverse gyno that's already there.