ehem...
this should clear it all up.
Sustanon 250:
30mg Testosterone Propionate
60mg Testosterone Phenylpropionate
60mg Testosterone Isocaproate
100mg Testosterone Decanoate
The prop and phenylprop are short esters, so after 48 hours they will be gone. injecting 1ce/week will only maintain effectiveness of 160mg out of 250mg for the entire week, the rest will be only in effect the first two days. so in essence 5 days/7 only 64% of your Sust is effective, while 2 days on, 100% effective.
Overall, your sust is 74.4% effective if injecting once a week, so your wasting 1/4. Not the end of the world, but jabbing a couple more times a week would be worth it.