There are so many factors that determine whether 1 or 2 or 5yr RP is given. I know someone who used a reputable agent and got a 2 yr RP and then the following renewal was only able to get a 1 yr RP. No reason given. I also know others that have work permits with no expiry dates (Chief Reps) who have been here over 20 years and can't get more than 1 yr RP due to lack of WP clear expiry date. And someone else i know is not able to get more than a 1 yr RP since he once was late by 1 day to move his RP from his old passport to his new one (the requirement is 10 days from receiving new passport). All these examples are Shanghai based so YMMV.