Although aircraft differ, every rack and rail setup I have encountered has one of the two seats with enough room in front for a bag, and the other obstructed. The middle belongs to the pax without room for a bag in front of them.

However, I will note that every (non-bulkhead) seat I've been in has enough room to stretch my feet out to rest on the crossbar of the seat ahead, regardless of obstructions. The gap is wide enough for a leg, at least mine.