I'm sorry but that's not correct.
Weekly dosing is not the way the product was designed. People should read the Organon pamphlet. There is a copy located here:
http://emc.medicines.org.uk/emc/assets/c/html/displaydoc.asp?documentid=5202
Sustanon 100 is designed for dosage every 2 weeks
Sustanon 250 is designed for dosage every 3 weeks
They arrived at the optimal layering of esters in each product to provide constant blood levels at the specified dosage interval. In the case of Sustanon 250, 3 weeks. It's meant to be a supperior (more constant, longer lasting) testosterone product for replacement therapy. Meaning not designed for building muscle on a 1 week injection interval which incidentally does not mitigate the effect of compounding long esters and building blood concentrations for the first few weeks of a cycle administered as such.
With more frequent injections (i.e. anything less than the 3 week design) you get instability due to the short esters. A mg to mg comparison doesn't tell the whole story because the ester weights for the long esters are significantly higher (i.e. in the same 1mg dose you get more testosterone from a short/light ester than a longer/heavier one). This further skews the product's testosterone composition to the shorter ester range than a simple mg to mg comparison would indicate. You can get an idea of this on the pamphlet where under the ester breakdown for Sustanon 250 it provides "equivalent to 176mg of testosterone" - I imagine the weights of the esters make up the remaining 74mg. Roughly 30% of the total product by weight.
All that said, plenty of people grow well on weekly dosages. 2x per week is probably a little better. If you are taking 750mg, why not do every couple days like prop and nix it. As to how much effect this has upon gains or sides, it's never been studied so no one can say.
I just have a pet peave about people saying it was designed for weekly injection intervals when the whole idea of hormone replacement is to make therapy as convenient as possible and the general public widely favors fewer injections.