Oddest I would say was Terry Pendelton. I sent him an 87 Topps 3 years straight for Spring Training. Never got anything back until middle of this past year. Odd thing is that I got all 3 of my 1987 Topps signed send back to me in one of my SASE's. So Terry must have hauled his mail around for 3 years and finally sat down and signed some stuff this past season. Interesting to say the least. I would have been happy to simply get 1 back, the 3 made me ecstatic.
I'm guessing on the normal day when the mail comes, a former player maybe busy or on vacation and their mail dosent get signed immediately. So the mail starts to pile up. On the day when they have nothing to day or pile of mail too high, they spend an hour or two signing. Thats why if you watch the TTM threads or successes on SCN some players autos come back in bunches.