I just put some on my sons Bronco evenly spaced. They look good. But most trucks you see the side markers with the three center clearance.
I kinda like the evenly spaced. But more opinions the better.
The stock lights were evenly spaced from the factory. The newer truck have them spaced out unevenly, but the older ones like we have were all spaced the same from the factory. If I recall correctly when I put them on my old truck I spaced them on 12" centers and 1 5/8" back from the drip rail. Here is a thread that has the how-to. Page 2 has the measurements.