We've automated the invoicing and $ metrics part so there is not really that much to keep track of manually.

I get where you're coming from but the reality of B2B SaaS is that you'll almost always have factors that will make some differences in your $Rev per customer/seat.

Think about a) offering discounts to some customers b) different prices per seat tier c) old pricing plans etc etc

The goal needs to be to increase your CLTV over time and unfortunately this often means increasing prices, changing old pricing tiers/plans etc.