One thing is that Sustanon was developed as a blend of esters to provide even blood levels for longer than standard single long-ester solutions. It was specifically designed to be injected once every 3 weeks (I have a link below and if you search my posts in this forum I did post a pdf link to the package insert from Organon). This is specifically why these esters and the resulting proportions were used. So it is in no way optimized for BBer use or weekly injections. One more thing to consider is that when you look at the different esters a mg to mg comparison doesn't really provide an accurate picture of the composition of the blend. You have to also take ester weight into account. It's significant - look at acetate vs. hept. (parabolan ester I can't spell) the amount of active ingredient per mg after the ester is removed varies significantly - 100mg of acetate is not the same as 100mg of a longer ester. This further squeues the balance toward the shorter esters more than one would think from a simple mg to mg look.
So anyway, that's the jist. It's just not designed for injections more frequent than 1 every 3 weeks. They also have a separate blend for injection every 2 weeks. What does this leave the BBer - the task of figuring out how to best apply a compound not specifically made for their needs. Given the blend and factoring ester weights to really get a good idea makes the calculations onerous. My personal opinion is that it's a hell of a lot easier and often cheaper to use a single ester and manage your frequency. Of course, how big of a deal is it - it's not life or death and obviously good gains can be made using it even 1x per week. As far as what is optimal for even blood levels, given what I've already covered, it's a frequency that balances out the short esters. How much more optimal and is it worth it for people to do it? I don't know (maybe use a spreadsheet, figure the ester weights, apply halflives, calculate the deviations, and chart it) it also likely depends on the person and how much he wants to bother himself with it.
That's my take on sustanon and that's also why you hear people talking about more frequent injections than 1x per week. Obviously from what I presented I think they are correct but I doubt that the majority has any idea and is merely repeating what someone else told them. So anyway, check out the link below and maybe search up the organon document I linked a few months back. I'd love to see such a spreadsheet made up but it's not something to which I'm willing to devote my own time since my involvement is zero. Personally, I think a comprehensive spreadsheet (still an estimate to some degree but a lot more accurate) would be a good basis for decision making and looking into this further. Afterall, this is how they designed the drug in the first place using simple calcs and analytics.
http://www.dundee.ac.uk/medther/tayendoweb/images/sustanon_injection.htm