So, I just got done threading 1,104 warp ends for my 12" wide sample warp, which took me a little over three hours of work (total; I split it up through the day so I wouldn't get too tired).
Along the way I discovered one little trick that was ergonomically more efficient: instead of threading with the hook facing down (which is how I sley the reed), thread with the hook facing up. That makes it easier to grab the loop with your first finger as the hook comes out from the heddle, and secure the loop as the hook is going into the next heddle eye.
Before, i was threading with the hook facing down, and had to do an awkward little wrist flip to secure the loop of thread before going on to the next heddle. This is much quicker.
Anyone else have tips to share on efficient threading?