Solid Hardwood, Engineered and Laminate Flooring - Engineered wood - a few questions?

After looking at hundreds of wood and laminates I finally settled on the "Mullican Meadowview Oak Saddle" engineered wood. I haven't decided yet whether to go with the 3" or 5" boards but at least I've settle on the type and color to match my wood work. Since I'll be installing it via glue down method I'd assume using the 5" would be somewhat less labor intensive. Is this a correct assumption? Also, I've heard varying opinions on getting from 5% to 10% more than my measurements. What do you experts say? Finally (at least for this time around) if I were to go with the 5" boards would it make any sense to order a box or two of the 3" which is identical except for the width to preclude a little less cutting and waste as I near some of the walls? thanks in advance for your responses....

You will likely cover the area a little quicker by using the wider planks. Calculating 5% extra for waste and cuts is the industry standard. It would be difficult to calculate how much ripping our how many boxes of 3" planks would be needed. Stay with the 5" and rip as needed. Follow manufacturers recommendations for acclimation and installation.

You do get a little more waste with wider boards, especially on angled walls, or a 45º layout.