You’re right-KB3138612 was once essential because it included major improvements to the Windows Update Client, specifically addressing the infamous “checking for updates” hang on Windows 7. Even now, it occasionally surfaces in troubleshooting guides since it’s a prerequisite for later servicing stack and update client fixes. For truly fresh Windows 7 installs-where Windows Update is broken out of the box-having that patch in place can still be the tipping point for getting the update process unstuck before layering on the latest cumulative fixes.
That said, in 2024, most guidance referencing KB3138612 is outdated. Windows 7 is out of support, so servers and catalog metadata aren’t updated the same way, but there isn’t any technical necessity for this update if you’re already up to date through ESU Year 3. If you’re building a Windows 7 machine today, it’s faster to manually layer in the latest servicing stack update, then the latest cumulative rollup. Installing KB3138612 specifically is very rarely needed anymore-unless you’re fixing a totally offline or legacy deployment.
In short, it’s mostly inertia at this point. For modern scenarios, skipping straight to the most recent SSUs and rollups is the better approach.
