Will P90X still retain some of it's effectiveness if I only have the

[BDBroncosFan]

time to do it once per week? My time is stretched pretty thin between family and a time-consuming work schedule. I only have one day per week that I have time to actually work out. Will this system still be fairly effective or is there something else that might have more benefits as far as muscle growth? I'm doing it to gain muscle, not lose weight. Thanks in advance!