Accommodations often get overlooked for rear walls and other obstructions, like a front rail or low "pony" walls between rows, due to the common misconception that all rows need to have the same dimensions. However, this causes the seating to bump into the obstruction and cause a ripple effect of issues throughout the rest of the rows.
In the case of a rear wall, for example, when the tread of the last row is the same depth as the previous rows, the chairs have to be installed further forward on the tread to account for the back overhang. This shortens the length of clear passage between the back row and next row, which causes the next row to be placed further forward on the tread, and so on down each row. This creates a gap between the rise face and chair back, as shown below. A patron’s foot can easily slip between this space, or personal belongings may fall into this space.