Just to clarify, leaving batts on a tray until they reach 0 volts is not "dead shorting".
Dead shorting is when you have brought the volts down with a tray, and then you take it off the tray and connect the positive terminal to the negative terminal on the same batt. This is called dead shorting. It brings the batt down to 0, but not in the same manner that a tray does and may cause the cells to explode if you haven't brought the batts volts down far enough first.
Using trays to bring the batts down to 0 is perfectly fine in my opinion. I did some extensive testing on discharging and equalizing and looked at the results with a Futaba CDR-5000 and what I found is the longer you tray them, both in between race days & in between runs on race day, the better the pack will be as far as run time and resistance goes. The voltage stays the same, but you actually get more power with the lower resistance and it drops off less throughout a run.
During the race day, discharging them with a 30a bulb tree & then traying them until the lights go out is a MINIMUM. In between runs, I leave them on the tray as long as I can before I have to take them off, ALLOW THEM TO COOL OFF FIRST, and then charge them. I realized through testing on the Futaba that using the same pack for all qualifiers and the main will allow the battery to operate at its peak performance by the 3rd run. All of this testing was done with GP3300 matched packs from Pro-match, Integy, Fusion, Peak & SMC.
Out of all of these packs, the best matched ones from SMC and Pro-match are the only ones that haven't produced a bad cell over the last 8 months of hard use. My worst matched SMC pack did produce a bad cell very recently, but I'd attribute this to an error in charging strategy during hot weather. I have to admit that I use them very often every week with anywhere from 6 to 16 runs during track testing and an additional full race day of 4 to 7 runs. Of course I'm cycling through using each pack, but each pack on average gets around 4 to 6 runs per week. The SMC packs with the closest matched numbers and lowest IR have actually gotten better over time and they are currently used for race day. The Pro-match packs with the closest matched numbers have about the same performance numbers they did when I bought them.