I haven't used my e-credits to upgrade anyone else except for family. All my upgrades were from my wife's account (E50K) nominating me (~15). All except 1 were on a flight pass, most went to the gate (at T-4 or T-5) and on many of these flights I beat out SEs nominating themselves.

The only upgrade I missed was on a Flex (T) fare, and there was only 1 spot with at least 2 other SEs outside of me waiting for it.

It's not hard to extrapolate based on this.

Next year this problem will go away somewhat, as nobody (except SEs) will have nominees. With upgraded companions required to be on the same flight, I imagine we'll figure out how the system works pretty quickly. Hopefully the companions will clear with the same status as the Altitude member, otherwise you'll wind up with a lot of spouses sitting in the back!