how neccesary is a return line for a electric fuel pump?

Not sure if this applies, but I was reading an article by Ford, about fuel injection on their Fox bodied cars, and it said they don't recommend a return line due to it picking up heat. I know this contradicts what is said on this forum, but this was written by their tech guys.

Oddly, the 86-98 Mustangs do have a return. I think 99 was the first return less system.