FRA-YYZ a week ago, the very helpful AC MLL front desk reminded me not to board until the list processed, hinting it wouldn't be till after boarding started. I was in Y, with 7 ahead of me in the J list from PY for a 36/40 J, looking like a PY eUp only for me. But noticed a few hadn't checked in still on both the YYZ and YUL flights at T-1h, so I thought.. mmh, maybe some mis-connects here (it was thick fog earlier in FRA). Anyways, boarding started, I jumped up 1 place then another which was just enough to make it to J... 10 min after boarding started.
i guess big hub airports like FRA have the potential for a last minute shift of fortunes for some at the misfortune of others!