I was actually wondering this myself, because this year was the second year in a row that all six sororities at my school had to COB. Our total is currently 75 and 4 of the houses usually hover around there while 2 others are usually anywhere from 15-35. One of my sisters is Panhellenic secretary/treasurer this year, and when I asked her about it, she said that they can't lower total because the only reason quota was so low was that many women (54 out of 167!) had dropped out of recruitment. If everyone had stayed in recruitment and gotten bids, quota would have been higher and the 4 bigger houses would have hit total without a problem. So basically, if there was lack of interest in formal recruitment to begin with, they would have considered lowering total, but since the interest was there and women dropped or didn't get matched, there's nothing they can do about it. That's my unofficial second-hand information about how changing total works; hopefully someone with more expertise in NPC rules can come and explain it for real.
