Within distance limits it's max. 16 segments (also transits do count towards total distance, not just stopovers) one stopover in each city allowed (+max. two transits on top).

OW awards do not necessarily need to be RTW in nature, if that has any relevance to you..please also note that as per current rules you have only 1-3 days from booking until ticketing (=paying the non-refundable taxes + fees) with OWAs, depending on your status.