Well, I did say "technically." To keep blood levels up, one shot prior may help. It doesn't take long for blood levels to increase from a shot of AAS, even with a long ester. You can verify this by having blood drawn before a shot, and then one day after the shot. I have seen my blood tests of test cyp go from below 200 to over 1700 in one day. Now for the body to actually respond to it is another story, but considering he's already been using NPP, his body may use the longer ester deca just the same since blood levels would peak in 1-2 days and his body is already responding to nandrolone. As long as he takes a large enough dose, he should be fine by the time he returns in the way of half-life of the substance. Also, it's only one week. I doubt he'd lose any muscle unless he didn't eat, but then even if he's on and doesn't eat he'll lose it.