> That is, if you tell someone they have 60 days to finish a task that could be done in a week, most often than not people will use 60 days.

This happens in mostly too situations:

- the person has absolutely no stakes in the game, and you are the only one caring whether it takes 60 days or not. Typically if you are paying them based on their hours worked as a contractor.

- The person understands that the task or the deadline is bullshit and nothing will important will happen whether it's finished in 60 days or not.

Either way, it's never a great situation IMHO.