Because schema changes and deployments are generally non-atomic, running a transaction through an untested configuration (front-end code = 1.0, schema = 1.2 and

Because schema changes and deployments are generally non-atomic, running a transaction through an untested configuration (front-end code = 1.0, schema = 1.2 and backend = 1.0) generally results in unknown things happening. When dealing with money people generally prefer right to fast.