I have 2 landings that I am using Garrison engineered 3 3/4 planks. The landings are 3 ft x 4 ft. Would it matter if I didn't stagger the planks and just installed them all one length? I plan on gluing them down

It's all a matter of personal preference. The same holds true when using plank on stairs. Personally I've found some customers love the random look while others almost get sick of the idea.