There is a definite advantage.
From Why Aren't You Growing:
4) Training a bodypart once per week (and one bodypart per day) is one of the worst ways to train.
It will create a rut in your training that you canít dig out of.
Training a bodypart twice per week has always been shown to be superior to once per week training of a muscle. The problem is with the influx of "Weider Principles" and other bodybuilding trash that's posted in the magazines, the masses have been stuck in the one-bodypart-per-day-per-week rut for years.
No strength athletes train a bodypart once per week. Most olympic lifters, powerlifters, and strongman train their backs at least four times per week, and last time I checked, they weren't lacking in back width.
The simple fact is that training using an upper/lower split or a push/pull split or 3 full body days will provide double or triple the training stimulus than training a muscle once per week and thus, if done correctly will lead to much, much greater growth and strength gains.
Originally Posted by Kane
It all depends on the routine.
I think it depends more on the individual then the routine and the fact is that those who respond better to once a week "volume" routines are the exception rather than the rule.