Engineered lumber is not and should not be sold without an engineering plan which is very specific as to how it is installed and used.

One potential drawback with continuous lengths is that you can experience increased vibrations. Jump on the floor at one end, and the floor at the other end responds. some manufacturers have ways of adressing thios, parting the lengths is one of them. Any repuatable retailer of engineeered lumber will be able to chech your pl,ans and certify the design for you before ordering.

Excellence is its own reward!

Generally, no matter what kind of lumber used in a project, engineered or not, shorter is easier to handle. Unless there's a specific engineered or physical requirement in the plans for lengths over 20' (like rafters), using 20' and under usually keeps handling as a 2-man project at the most.