Yeah, Lake County can be a little confusing...
Kirtland PD mostly uses the shared talkgroup with M.O.L. and Lakeland on I.D.# 336. But you'll definitely want to listen to 151.205 as well, since there is a lot traffic on there that you won't hear on the Lake County System. Also, Kirtland Fire and EMS share I.D.# 2416 with Willoughby Hills Fire.
And as for the Lake County System, only 3 cities have their own talkgroups for police dispatch...Mentor, Eastlake, and Willoughby. My guess would be due to population, since these are the only 3 cities with over 20,000 people.
Now every other department has their own private talkgroups (1A, 1B, etc.), but they have to share dispatch channels:
Willowick and Wickliffe share...Willoughby Hills and Waite Hill PD's share...Painesville, Fairport Harbor, and Grand River PD's share...Madison (Village and Township) PD's, Kirtland Hills PD, and the Metroparks Rangers share (dispatched by "Central")...and last but not least, the Sheriff shares a channel with the Timberlake and Perry PD's (also dispatched by "Central")...
Now personally, I think Eastlake should also be dispatching for Timberlake, for officer safety and mutual aid purposes...But for whatever reason (probably the fact that Timberlake owes Eastlake money), that's not happening. However, you will hear a Timberlake officer on Eastlake's dispatch from time to time, asking them for backup. Also, Wickliffe and Willowick PD's help each other out a lot, so sharing a channel seems to work out very well for them (same can be said for the P'ville/Fairport/G.R. setup).
The only thing that doesn't make sense to me is having Mentor on the Lake share with Kirtland and Lakeland College...I don't get it. I know M.O.L isn't exactly a huge city, but the Police Department is usually pretty busy. And since they don't border Kirtland or Lakeland, I don't see why they can't have their own talkgroup for dispatch (I'm sure there's a reason, but I just don't see it).
Anyways, the Fire Department dispatch setups are a little different (M.O.L. and Painesville City also have their own dispatch channels along with Eastlake, Mentor, and Willoughby)...But you get the idea; everyone else has to share.