Is there a term for tending to underestimate the sum of many small numbers? (i.e. time)

Web: https://www.reddit.com/r/productivity/comments/ullx4g/is_there_a_term_for_tending_to_underestimate_the/

Not sure if there's a psychology term for this. E.g. it'll be 10am, you quickly cook and eat, then take a 15min shower, reply to emails for 15min, take a 30min break, etc. You feel like maybe 2h has passed, but it's already 6pm.

I'm assuming most people experience this? What is it called?

productivity time