Has anyone here layed a floor that came in two lengths?

I will be gluing down engineered hardwood on a slab. The wood comes in two different lengths, 18 and 28 inches (same amount in each carton). I know about cutting the starter boards to create a random length and keepting joints at least 6" apart, but how do I lay the 18" and 28" boards AFTER the starter board?

I called the company twice and spoke to two "techs". Person A says to cut the starter boards then alternate, IE 18, 28, 18, 28, 18 etc and cut the last board to length. Start new row with new starter board size and repeat, 18, 28, 18, 28 etc.

Now,

Person B says basically the same thing BUT do not alternate, mix up and use something like 18, 18, 28, 18, 28 28 etc so there is no pattern.

So I'm now confused and don't know who to believe. Do I alternate between the two lengths or mix it up??? Help!

What would you do?

Person B, Mix it up, or your going to have a pattern to the floor.

Will take your advice.
Thanks Floorguy!!

(I still find it amazing how someone can get two different answers from the SAME manufacture).