What is the industry standard for joint spacing across rows of floor planks?
I’m not sure if there is an industry standard. It is really an aesthetic issue. But in general it is best not to have 2 joints closer than about twice the width of the boards themselves. So if you have a 2 1/4″ wide strip try to have the joints of two boards no closer than say 4-5″. And I mean two boards, because the next ones should be farther and farther apart, so that you don’t set up a stair-step effect. It takes some years to master this technique by racking up 8 rows of strips across the room. Then take the time to add and subtract pieces until the joints are pleasingly spaced. And you should avoid H joints where the joint is lined up with another joint, with just one row between it.
All this said, everyone, (including me) will make minor mistakes in this pattern. In most cases it will be hardly noticed once your furniture and rugs are in. But if the floor is full of these busy, unsightly joints, it may be the installer who has let you down. In many cases he is paid very little on piecework basis, and will rush through your job, just to make a living. This has become the industry labor standard, sadly enough.