Which is frankly the responsible thing to do. Gives Operations, Scareactors, and standard guest flow a grace period to make mistakes, to block the conga line, etc without the actual wait time exceeding the listed wait time.
If TLoU is listed at 120 and is really a 50 or 60, or Yeti listed at 45 when it's really a 25, the average guest either doesn't notice or counts it as a fun bonus. The other way around is a massive problem for guest experience.