It's uncommon for a true wilhelm to have more than two flowers per spike. The larger lowland species (glanduliferum or praestans) which is often mixed in, maybe in the wild too (???), can have 3-4 flowers routinely.
Peter those are great looking flowers. What is the source of your plant, and how big is it?
I have one with blooms opening now too. Maybe we should breed 'em.
Very nice Peter.
As a passing comment, some descriptions of the origins of P.rothschildianum gave New Guinea as it home. Looking at this pic, for the early days, it could have been this plant they actually collected and described, depending, I suppose if they had actually seen the correct roth.