Of course it was designed to hit Trump hard, throw him off his game and to get under his skin, which it would do given his personality type...and did.
This had nothing more to do then Hillary having met with those who understand what can trip his personality type. It is the weak point of his personality to be sure.
I think Trump does understand this but still has work to do in building a firewall when it comes to personal attacks in the debates......more importantly to turn them back on her or use them to state what he otherwise would want to be made known that is favorable to him.
And yes, the difference between preparation for a political goes far beyond just issues rather understanding and knowing the weakness of your opponent and devising “zingers” to unbalance them. All Trump needs to do is build that fire 'wall'...when she will be doing this, and for sure will do so again.