ill usually just keep the final masters on my comuter. once i fell like the recording and mixing part is complete, and i approve of it........ill master it and save the master stereo wave file......................but ill end up ditching/tossing the project file and such away.
so in a nut shell,.....i just keep the masters on my computer.............if i kept the other project files and such........i would ALWAYS be changing the mix, and keep remixing it over and over, and over.........cause im never satisifed with my final products. But usually a person who records/mixes/masters thier own stuff never is.........were so anal that way.
yeah......toss the projects when your done with em, and keep your finished master. if i didnt,.......id still be trying to mix/master a song i did years ago........in which most people think its a great mix.......but im always trying to get more out of it.
save yourself the trouble! mix/master it!......and move on! resist temptation by purposly throwing away the project file!