By Bismarck.Helel 2011-05-15 15:48:55
There are a max number of boxes per zone. It happens ALL the time to me when I'm AoEing stuff on BLU. When there's a low number of people in the zone, every mob will pop a box (or close to). When there's 100ish in the zone, I'll be lucky to get 3 boxes per whisker. It happens because people aren't opening the boxes fast enough and therefore they aren't depopping. It also helps if you wait until the boxes you popped depop, and then AoE the mobs right after. All the boxes that just depopped will now pop for you again. Usually though, if you start getting 1-3 boxes per AoE, you're better off taking the mobs to low hp and killing them one by one instead of at the same time.
@OP, if the number of chests are not an issue, you either need to kill mobs that don't give ruby, pull more mobs, or level BLU. You shouldn't have any trouble getting TE's with capped ruby, but it will lower your chances, hence why BLU is a much better TE farmer.