Correct. Mostly because people don’t do extensive FTP blocks. If they do, they learn what riding at Threshold feels like and how to get comfortable (relatively) with riding at it (or likely 5 or 10 watts below it) for longer and longer periods.
A few weeks back I did a 4 week extensive FTP block and pushed my TTE out from 35 minutes to over 55 minutes.
Of course, there’s no reason one has to do such training, unless a) it’s event-specific or b) you’re just curious.