Closing duct runs that run past last vent

Cecilt wrote:
My non-engineering brain tells me logically that if the duct stops at the vent that all the air that hits the blockage will be forced out of the vent and hence much more air into the MBR and bunkroom.

This is correct and that might be what the manufacturer was attempting to avoid and the simple solution is to just leave the actual duct open at the end.

Keep in mind that even though the duct is currently open at the end, the duct is in an area that is more or less closed, so the boundaries of the area itself becomes the actual terminus of the duct. The fact that the area is not air tight is what helps "soften" the flow out the vents on the line, giving the owner the perception of steady flow out each of the ducts.

I hope that explanation makes sense.