
you could do that, but...
The record is clear that "employee training" does not work well. Partly this is because of box-ticking exercises, but also it is because it takes only a single incident to cost a company a huge sum of money (and possibly damage to its reputation). I'd suggest that a better option is to provide the great majority of employees, most especially those in accounting, finance, payroll, AP, AR, HR, and other internal departments, with internal-use-only accounts that cannot send or receive mail outside the company. Invoicing and similar tasks can be completed using fax or postal mail, as they always have been and as every company is set up to handle anyway. The only employees who are likely to need outside email access in most companies are the sales team, and they need to have their accounts set up with the strictest imaginable settings and receive at least weekly anti-phishing tests (no pass, no pay; salescritters are easy to motivate, and besides that most of the scams will be obviously irrelevant to someone in that role). And since they don't normally have access to the company's accounts, even when they do inevitably fall for some scam it shouldn't do much damage.
In principle, humans are smart enough that this crap should never work. In practice, it's apparent that any collection of 10 or more humans likely has at least one who isn't. Let's be data-driven in our approach to security.