I posted this in another thread but it may have been off subject and/or the thread was dying.

The other day I was tuning up my brothers mountain bike had 9 cogs in the back, and I adjusted it well enough for the chain to move to each cog without flaw however there were still extra shift clicks in the shifter. This puzzled me but I could not adjust anything enough to get it to just have 9 clicks. So today I was adjusting my front derailleur on my Fuji touring bike, 3 rings up front, and although there are only 3 rings my shifter was clicking 4 times. I brought this up to my mom who has a new Fuji road bike and she said hers and her boyfriends bikes do this also and it's probably supposed to happen. I read something on Sheldon Browns website last night on something called trimming so are these occurrences related to that or is this something just different altogether?

You should only have extra clicks on the front shifter.

Extra clicks out of your rear one may be a sign of busted internals. How well does it shift?