Shed pier foundation quesiton

Hello, I am going to be building a 12 wide x10 deep shed with a 12/12 pitch roof and have a question about the foundation. I live in the upper midwest where we have hot summers and very cold winters so frost heave is an issue. I will be using nine 8"x4' concrete piers for a number of reasons. The bottom of the shed will sit on 3 treated 4x4x10s (as all shed plans have called for that I have reviewed) I have not found a definitive answer on the best approach with this method - here are my questions. Many people have said that between piers there should be concrete blocks to support the skids. This is confusing to me, and counterintuitive. Yes, I understand that adds support, but doesn't that create issues when there is frost heave?