With a 720 you are already above the averages for top schools. I think you would be better off spending time on essays.
He said he isn't applying for a few years so he has plenty of time for that. Honestly though the hours spent studying may be better served volunteering or doing something else to strengthen your profile. Definitely give it another shot since there is time and room for improvement. But if you dont get a much higher score, you are is above every schools average so limit it to one chance.
I know of a person who started with a 730 and went up 20 pts on a retake and then amazingly with a 750 actually retook it because their Quant dropped from a 51 to a 50. People can become obsessed with the GMAT, dont become one of them.