Really, 3 whole minutes?

Some good, fun early morning running again.
6.5 miles got did.
Another little pit stop halfway through, but happy that I went back and finished.I need to start getting up 5 minutes earlier to avoid such pit stops ;).
(to, ya know… work things out.. hmm- TMI?) 
Now I would like to discuss something else.
Yesterday I was reading an article in Runner’s World. It was Breaking All the Rules by Alex Hutchinson.
It said THIS:

 Well, I am not questioning the slower long runs. That seems to be widely accepted.
But 3 MINUTES per mile slower than race pace? That’s the most I have ever heard of and seems excessively slow to me.(I DO try to run my long runs at a slower pace- work in progress.) 
How much slower do y’all do your long runs? Should I be doing mine 3 minutes slower? Can you tell that I am still new to running?