If a shipping method is selected, require a shipping address

We often have to go back to the customer before an order is shipped because a salesperson forgets to enter a shipping address or the customer will get it to us later. It would be nice to have it required on certain methods.

It could be done on the shipping method side. USPS requires an address; if no address, a prompt comes up when saving the quote/order. 

We have a storefront so most orders are pick ups, so it doesn't make sense to get an address from a bulk of our customers. But we also ship quite a bit so it would be a big time saver.