What is a primary benefit of consolidating traffic through a central bastion/transit network in a...

Acentralized bastion or transit networkimproves hybrid cloud security by:

Reducing cloud sprawlthrough a unified security control point.

Centralizing firewall, logging, and security monitoringfor betterthreat detection and response.

Enforcing consistent security policiesacross different cloud platforms (AWS, Azure, on-premises data centers).

Minimizing unauthorized lateral movementwithin hybrid cloud environments.

This concept is extensively covered in:

CCSK v5 - Security Guidance v4.0, Domain 7 (Infrastructure Security)

Cloud Controls Matrix (CCM) - Network Security and Monitoring​.