4 tests to test effectiveness of customer segmentation scheme

Since there are multiple ways to segment a customer population, how do we know we have arrived at the right behavorial clusters. Here are 4 simple tests to test segment for effectiveness
1) Is the segment actionable?
2) Does the segment have a critical mass of shoppers for the retailer to warrant a specific value proposition tailored to the segment?
3)Is the proposition required by each shopper cluster sufficiently different from that required by other clusters?
4)Is each cluster reachable through communication and sales channels the company can use and for communication purposes?