Mastering Configuration Manager Bandwidth limitations for VPN connected Clients

Thanks Stefan.  Sorry I'm more confused than ever now.

What you're saying is what I assumed; older versions of W10 will have much larger CUs, due to their age and thus large amount of CUs rolled into the latest ones.

The newer OS versions have much smaller CUs.

But then does this mean:

Express Updates:

Before Windows 10 1803 you had the possibility to use Express Updates to reduce the amount of data that needs to be downloaded from a client. If most or all your clients are above 1803, don´t consider enabling this feature. It will add a lot of overhead to your infrastructure and clients.

... that because of the smaller size of the CUs (1803 onwards), it's simply not worth implementing Express Updates?

I was reading it as; there is a larger compute, storage and bandwidth cost related to the primary DP to additional DPs data transfer - for 1803 onwards.