The real problem of Evergreen IT Management isn't figuring out how to efficiently (and, let's face it — fast enough) migrate your entire estate from one version of Windows 10 to a newer version. It also isn't the volume of change if you are managing your Windows 10 OS lifecycle in conjunction with Microsoft 365 Apps for Enterprise in addition to a continuous hardware refresh. That all can be managed very well with the right tooling and automation. The real dilemma goes much deeper.
In my opinion, the dilemma that most enterprises and large organizations struggle with emanates from the very intricate dependencies you simply cannot get around when managing Evergreen IT. In other words, you have to upgrade a whole other slew of infrastructure dependencies — each managed by a different, siloed-off IT department.