The phrase Advanced Persistent Threat has been around for some time. It has since been generally adopted to refer to crafted, long-term attacks on larger organisations. But targeted attacks are very different from your everyday malware, and testing protection against them turns out to be a very different kind of task. A product which provides a better range of protection against all sorts of attacks offers you a better chance of avoiding being hit by anything. The point about targeted attacks is that they will take all factors into account when designing their strategy.”]
Source: https://nakedsecurity.sophos.com/2014/03/12/can-we-test-protection-against-targeted-attacks/