Thank you that helps a lot! Would 3-3/4″ wide boards on either side of the walls in the hallway be to narrow? In other words, I’d have 3 full boards in the middle then on either side of those 3 boards I’d have 3-3/4″ boards. Would that look tacky or be ok?

Which direction should I start from? The bathroom wall or the wall with the closet and bedroom?