ive said this before, but there are a couple of schools of thought regarding how efficacious stable blood testosterone
values are in terms of muscle building in the first place, so the actual NEED for stable blood values is questionable, imo.
anyway that being said, i think that the thing to think about is pain/infection risk vs benefit of having stable bloods, and since Sustanon is formulated to be shot monthly (or 3 weekly) common sense would suggest that once a week is more than enough.
anectdotally, the gym i used to frequent was a heavy roider gym, and the accepted practice was to shoot once a week - and these guys got really good results ie comparable to the best results i see reported here as per a few polls ive made
that being said, its your (your pincushion) so do what you like.