[rules-users] Complex rule

Not really sure how to go about writing this in a rule or whether or not the logic belongs in a rule (I think it does, but if you don't please comment as to why). I have a list of objects that contain date objects. If the list contains 10 objects that date are before mine then I want them to take a break. The business case is similar to that of an HR system. If they have worked too many days out of the last 12 then they need to take a break. I am guessing it would have to use the "collect" attribute, but how would you do the date logic in a LHS clause? Thanks for any guidance on this.