A belated reply, but anyway...
I used to do some spring cleaning of my short lists at the end of the season. OK, it's technically summer-cleaning, but you get the idea. Every player aged 31 and above was removed (I used to think that 30 year olds were ok for some reason) and all those players in positions I didn't need cover for were also removed. Of course, by the end of the season, you had a good idea of where you needed to strengthen your team, so this is the reason for the position cull.
Obviously, there was always a risk the hidden gems would get removed, but what they heck. This kind of cull would also get rid of those players scouted while pished, as is frequently the case.