Sust and deca have very similar half-lives (both around 14-15 days) so it makes sense to inject them on the same schedule. Twice weekly is plenty often enough (1/4 of the half-life).
The only time I break up my injections is if I am doing a gram of sust or more. Even then I shoot it all on the same day. Deca as well. One set of shots in the glutes, the other in the quads or delts. Splitting up sust injections by a couple of days wont do shit except make some part of your body always sore. It just leaves more room for error or a missed shot due to some un-forseen problem. Shooting it all at once has always worked for me.
The only time I break up my injections is if I am doing a gram of sust or more. Even then I shoot it all on the same day. Deca as well. One set of shots in the glutes, the other in the quads or delts. Splitting up sust injections by a couple of days wont do shit except make some part of your body always sore. It just leaves more room for error or a missed shot due to some un-forseen problem. Shooting it all at once has always worked for me.
I do the same as latimer says. seems to work fine and less room for error, ie: abcess, infection, hitting a nerve, etc...that shit hurts, especially if you hit the psycotic nerve in your ass. lol