What type of test is it?? Prop, Enanthate, Cypionate??
If its E, or CYP then once/week is fine.
People just like to inject more to make them selves feel better and have a bit more stable blood levels.
Endo doctors usually give injections only once per two weeks, but thats pushing it considering Enanthate has a half life of 10 days, Cypionate about 14 i believe.