[@EurmalEye] the primary benefit of a set posting order is that everyone gets an equal amount of posts. For example, if we have 5 players and 50 IC posts, then everyone should have exactly 10 posts. This is better for people who are only able to get online for a few hours in the evening, since they won't get left behind by other players with more free time. The downside is that if 5 players all take an average of 24 hours to post, the RP will only advance by 7 posts a week. 

An open posting order means that those with more free time will have more posts. For example, if we have 3 players who are able to post during all daylight hours and 2 players who are only on in the evenings, our first 50 posts might see 12 posts each from players A, B, & C but only 7 posts each from players D and E. The advantage here is that the RP can advance much faster and there's no pressure of other players waiting on you. The downside is that it's easy for some characters to get left behind - it can suck logging on after a long day of work only to find that the conversation your character was right in the middle of has ended before you got to say everything you needed to.