Feliway Placement

Hi all,
I have heard two different schools of thought re feliway placement and I'm wondering what you all think. Some folks say not to put it right near the box (my cat has had a few litter box issues...) and some say the closer to the box the better. What do you guys do?

When a new cat arrives or when I go on vacation, I put Feliway plug ins in the major rooms. The outlet in the room where I have the litter box (the box is in a closet) is about 5 feet away, and I've never noticed any problems.

It's enough to plug in the diffuser in the same room, because it covers 50 - 70 square meters / 538 - 753 square feet.