Yes, one bigger dose per week will do a better job at keeping SHBG down. I've tried both ways, each over a 6 month interval with labs to see what works best for me. My SHBG naturally hovers in the 90's. With a single 150mg injection per week, SHBG hovers in the low 50's. With 2 x 75mg injections per week, my SHBG will hover in the 70's.
At the surface, and purely from an SHBG control perspective, it would seem that the single 150mg injection would be the better route. What I did notice from the 2 x per week dosing, is that sides were much better under control. For example acne has subsided quite a bit, anastrozole is rarely needed, mood is much more stable, etc.
Currently I'm doing the 2 smaller doses per week, albeit at a slightly higher dose per shot. I keep my TT in the ~1350 range, yielding a FT of ~20.
Pros & cons either way...It's a matter of what works best for you.