People who stock up on necessities as a normal part of their lives would have been stocked up already and typically only buy these things to backfill from their current consumption. I don't know if this applies to toilet paper, but it's common in the LDS community to have at least 6 months' supply of nonperishable food at all times. Mormons don't typically buy 6 months of food at a time though, they just buy groceries at a normal rate to backfill their pantries via a FIFO rotation.

Of course, the rare occasions where someone would buy 6 months of something at a time--e.g. if they recently adopted a lifestyle and/or religion that encouraged this behavior--are easily absorbable by the supply chain assuming not everyone does it at once.