Let alone how many operators monitor sessions down for prefixes -- some ISPs deserve to be depxxxxx when they find out after one month (been there, more than once) the sessions are down, and they ask you why those are down, cutting and pasting the 'Idle (pfxcount)' in their email even. That is my personal view though. So max-prefix is good for peers, maybe for customers, hardly for transit sessions, and whenever you do it, MONITOR IT ;)=) A three- line perl / sh script on top of your syslog or during logrotate or so is advised if only that.
The "restart" option of maximum-prefix (which is available at list on Cisco) should solve that, since it tries to restart the session every n minutes to see if the prefixes are back to normal. But then again, not everyone uses it... Regards, Daniele.