I don't know that it's more organized on some ships than others--maybe it has to do with the crowds and their mentality / attitudes from one cruise to another.
It's been my experience overall that it's become a mess. Although we're platinum with Carnival, we just sit back and let the crowds crowd, the pushers push and the ill mannered be ill mannered. Then leave when it's quieted down.
It would be my advice to anyone doing the self disembarking that if they have a family, make sure they stay together and whether traveling with a family or alone, hope you or someone in your party doesn't fall under the feet of the stampeding herd.