SharePoint Online Subsites

DJ_Jamba The clear separation of responsibilities and permissions you've established is a testament to your team's thoughtful approach to designing an efficient and effective solution. While Microsoft may suggest moving towards a hub site architecture, it's important to remember that their recommendations are often based on broad guidance and may not align perfectly with your organization's unique requirements.

In this case, the subsite structure you've implemented seems to be serving your needs exceptionally well, with a well-defined permissions model that allows portfolio managers, program managers, and project managers to access the information and resources they need without unnecessary complexity. Changing the underlying architecture simply because of a general recommendation could indeed introduce more administrative overhead, as you've rightly pointed out. The burden of managing permissions across individual site collections, rather than the streamlined subsite structure you have in place, could outweigh any potential benefits of the hub site approach. My recommendation would be to continue leveraging the subsite structure that has proven to be so effective for your organization. As long as you can maintain the integrity of the permissions model and ensure efficient management of the subsites, there's no compelling reason to disrupt a solution that is clearly meeting your business needs.

That said, I would encourage you to keep an open mind to exploring the hub site architecture in the future, should your requirements evolve or if new capabilities emerge that could enhance your existing setup. But for now, the subsite structure appears to be the right fit, and I commend you and your team for developing a well-designed solution that is optimized for your organization's unique needs.