Hello I'm a bit confused in regards to updating the WIM in SCCM. I originally mounted the WIM using DISM and imported the updates which seemed fine. However it still installs them at the end of the task sequence, I thought it would actually install them to the WIM. I have since used the schedule updates wizard which I understand will install these to the image not just add them as a task to do?

Why have both? Is my understanding correct?

Using offline servicing/dism just injects the patches into the WIM. The patches won't actually be installed until after the setup windows and configmgr step when the machine is in the full os.

I find offline servicing can be helpful for some customers to get patches injected between build and captures (If they don't run build and captures monthly), but offline servicing can only inject CBS (Component Based Servicing) updates that are OS specific.

Personally, I don't use it at all I just use MDT and re-run a build and capture anytime there are new updates that need to be included in my reference image. This ensures all available updates even non CBS based updates are included in the reference

However it still installs them at the end of the task sequence

This is not correct. Assuming you injected them correctly, as I pointed out in your other thread (https://social.technet.microsoft.com/Forums/en-US/770fe8ab-7c00-4b2e-81b6-8118dfb67dd1/how-to-determine-which-updates-to-add-to-wim?forum=configmanagersecurity#5a5e57ab-ff5a-4008-8034-24680d99d141), it installs them during Windows setup (which occurs during the Setup Windows and ConfigMgr task as Justin pointes out).

Using schedule updates does the exact same thing (as I also pointed out in that thread) except that it automates the process and directly leverages the updates you have in the Software Updates feature in ConfigMgr.

Thus, why have both? Because DISM is the core process and tool designed by the Windows team and offline servicing is for those that want to use ConfigMgr. Once again though, offline servicing uses DISM to do the exact same thing in an automated fashion though without having to manually download the updates.

You could ask the same question for anything that ConfigMgr does; e.g., "Why have software distribution when you double-click on an MSI?" Same reason, automation and