If I did this, I'd only be for extra protection, but with a good firewall, you shouldn't have an issue anyway.
Yes, if you wanted to change it every week or every 24 hours, that'd be fine, but every 10 minutes seems overkill, and does ask why you'd, or your friend would want that.
Honestly, tell your mate there is no point. Hes probably only slowing his connection down than protecting himself more.