They may have individual idles, but the idle alias doesn't return it. yes, the $idle shout have a parameter for which cid you wish to query about, and default to 1. Ex:
The last time you talked in a channel was 1 hr ago
The last time you talked in a channel was 3 hours ago.
" " " 10 minutes ago..
If you were to echo idle for server 3, you would get 60 minutes, not your appropriate idle time of 10 minutes.