The vast majority of records produced over years are shipped with paper inner sleeves. As you know, paper ages and as it does, it sheds fibers. The small particles of decayed paper present a significant problem that few people consider, but should.
Record grooves are incredibly small, on the order of .0007” to .001” in width, so it doesn’t take much to disrupt the intimate contact between stylus and groove. Paper fibers certainly qualify and should be removed. Assuming you have a vacuum record cleaner, the paper particles will be swept away during cleaning. But how many of you simply slide that clean record back into the old sleeve? It makes no sense to spend the time and energy to clean an LP if it becomes soiled as soon as it is returned to storage.
It is imperative that your clean record is replaced in a new sleeve.
There are a number of good quality sleeves available today. The audiophile quality so-called rice paper sleeves are particularly good and strongly recommended. Whatever you do, don’t simply buy replacement paper sleeves and you are beginning the cycle all over again.
While you are at it, consider adding plastic jacket covers to your collection. Not only do they preserve the jacket but they also keep the LP inside cleaner. If you are collector, we don't have to tell how important it is to keep the jack in pristine condition. To many collectors (not audiophiles), the condition of the sleeve is more important in determining value than the LP inside (horrors!).
Sleeve City sells a wide range of both inner and outer sleeves.