Extend Active Directory Federation Services (AD FS) to Azure

Hi!

Im reading Extend Active Directory Federation Services (AD FS) to Azure at docs

We're about to extend ADDS/ADFS.

I know i get more opportunities when i use 3 subnets regarding segmentation/nsg, but i also get more administration. 

if i use one subnet for WAP and one subnet for ADFS / ADDS  instead of 3 subnets, like a infraservices network onprem. 

Am i missing something ? 

Best Regards