Your own documentation for setting up servicing rings has the "Semi-Annual Channel (Targeted)" as an available Servicing Channel: https://docs.microsoft.com/en-us/windows/deployment/update/waas-deployment-rings-windows-10-updates ...we've followed this guide and have started setting up our internal "rings" but with 1803, you've promoted it straight to the Semi-Annual Channel immediately and didn't first send it to the SACT servicing channel. The previous four versions (1511, 1607, 1703, and 1709) all went through CBB or SACT, so I feel that this approach was not well communicated by Microsoft. If I configured one of my rings to use SAC+30 days, those settings with 1803 will mean those endpoints will receive 1803 several months sooner than my 1709 rollout where I expected SACT+10 to hit my pilot endpoints sooner to prepare our organization for broad rollout. It feels like we followed Microsoft's guidance only to have it get changed up with 1803.
Microsoft