the only time i ever use one is if i have a lot of left over paper or i think that there are people that will wet the end of it and it will get closed to easy....

it is not necessary to have one in the joint, some people like it, some people dont... me personlly dont think its needed because can roll a fine joint without needing a roach.... when i first started rolling i would use one cuz i would roll it and it would be a kinda loose, so i would pack it some and then there would be left over paper and shit so i would stuff a roach in there...