If the record is long (say 64KiB), and the tape is low density (800 bpi), and the EOT happens at the start of the record write, that can take 7 feet of the 14 feet of post-EOT-marker tape. Hopefully the remaining 7 feet are sufficient to prevent the tape from unspooling from the supply reel. Records that long, or longer, were uncommon back then, though the IBM hardware did not actually put a limit on record length. 7/