Yes massive. Air needs to enter and leave where the vents are placed will determine where and how much. Hi vents and low vents will allow the max air flow with the smallest amount of open area.
In my cages, since the doors are single piece and open down they have a small gap all around the top and sides. With this, I place my vents high at the back of the sides and that gives even circulation. Granted, this is in my 12" high cages, so if the cage were taller I would probably add more vents lower down.
**Adriana - White 'N Nerdy!**
1.0 BP 'SunSpot', 0.1 Corn 'Freya', 1.0 IJ BTS 'Topaz', 1.0 ND bunny 'Licorice'