The WWE pay-per-view system is done decently well. For the most part, the idea of 13 pay-per-views works for the 52 week year and the idea of having one per month makes a lot of sense as well. However, there is some part of the system that's broken.
It starts with the garbage pay-per-views with gimmicky names and the effect of these gimmicks isn't getting over. There are some that work and some that don't, and keeping the ones that work is always a good idea.
WWE needs to keep the big named ones of Survivor Series, Summerslam, Royal Rumble and of course Wrestlemania. Another thing that the WWE needs to do is bring back some of the WCW concepts, and even some of the older concepts. Follow along as these pay-per-views are finally fixed using 2013 as an example.
The biggest issue is timeline. While there are 52 weeks in a year and 13 pay per views means one every four weeks, that's not how WWE does them. The erratic build up times make it much harder to design the standard storylines. This would fix that, as only one event would have just 3 weeks of build up, but it has the chaotic effect to where they could get away with it: The Royal Rumble.