Base Template Modification for VDI Pooled-Based and Assigned-Based

Hi All,
Currently I have both Pooled-Based VM and Assigned-Based. I would like to know how to do manage the Windows Patches or changes to base template?

Lets say the scenario is like this:-

I have 20 assignment based vm for my VDI environment. There is some requirement i need to do modification to all the 20 vm. Can I make the changes to my base template? and sysprep again? the 20 assignment will take affect? or i need to re-create the collection?

Also another thing is how do your guys manage the changes and windows patches in your environment? Thank you!