6.43A good high-level Mule flow

The top-level flow should ideally read almost like a business process:

receive-request
   ↓
validate-order
   ↓
ensure-customer
   ↓
obtain-credit-decision
   ↓
process-order
   ↓
publish-result
   ↓
build-response

Rather than:

Set Payload
Set Variable
Transform
Logger
Choice
Set Payload
Flow Ref
Set Variable
...

The implementation details live inside meaningful subflows.

This improves maintainability and testability.