Three SD-WAN engagements running at once, in a bank and a state legislature — environments that share almost nothing except that neither of them can absorb an unplanned outage quietly.
SD-WAN is sold as a simplification and delivered as a routing problem wearing a controller. The overlay makes path selection a policy decision rather than a protocol outcome, which is genuinely better, and it also means a mistake in policy expresses itself across every site at once instead of at one. That is exactly the class of change the routing-configuration review existed for.
The low-level design reaching revision 2.0 is the detail worth keeping. A design document that never moves off revision 1 has either been perfect or unread.
Outcome
Three SD-WAN estates delivered against one design language, with routing configuration reviewed before it reached production.