Unless you are using the rise to either slow the horse or to length or shorten it's stride. If you rise bigger then it will encourage a longer stride when combined with a stable seat and core muscles. nothing wrong with a full rise as long as it is in time with the horse and in accordance with what you want to do.Are you pushing off the stirrups? One should only post as high as the horses impulsion "throws" you in the air. Any higher and you're doing it wrong.