16 feet, or shorter, in length is fine. I do like to work with full length pieces at the start along the sheer, and perhaps at a few other places, to insure fairness. You can scarf the few pieces you need for stuff like that. Other than that I usually use butt joints...especially on the hull. Truthfully, I try to avoid any kind of joint on the deck except that which I need for the pattern, but if I need a longer strip I'll make a scarf joint. I always widely stagger any kind of butt, or scarf, joint...not just because of the strenght issue, which is minor at this point...but because it looks better to me. If you match grain on scarfed strips the joint is very hard to see when properly done. Use the search feature and you'll find much more about scarf joints and stripping.