In any enterprise, normal would be to have monitoring on all ingress and egress points from the network and on devices themselves. You can't only have monitoring on managed devices because someone might BYOD and plug in an unmanaged device/connect it to internal wifi etc.

You bring in vendors and they need guest wifi to give you a demo, you need to be able to give them something to connect to but you don't want that pipe to be unmonitored.