Not a useless analogy, it gets the point across that good estimation requires breaking a task down into little steps, questioning the requirements, discovering

Not a useless analogy, it gets the point across that good estimation requires breaking a task down into little steps, questioning the requirements, discovering constraints, and iterating. The estimation process doesn't change much whether you're painting a room on earth or on Mars. If there's more uncertainty when estimating steps, you add more buffer time for instance. The goal of the exercise is to improve your estimation. Where the room is located should simply be factored into your estimation process.