Forgive my username, there is nothing logical about this.
It's because estimates are really just a test of your imagination and skill. They're a "different game" from delivering something. Here are some examples:
How long does it take you to add 1 + 1 together? The only correct amount of time is "0 - no amount of time." But clearly that's not true, is it?
How long would it take you to multiply 5 by 7? Well, zero. No amount of time - you know it 'by heart'. It doesn't take you any amount of time to multiply 5 by seven. Well, clearly, that's not true is it?
How long would it take you to test whether 31337 is prime or not, by any means? Like, 1 second because Wolfram Alpha can tell me I bet. But clearly it wouldn't take me ONE second, would it?
How long would it take you to write a function to test whether an integer less than 2^32 is prime or not, without having to be super-efficient about it? Well like 10 seconds. But, clearly that's not true, is it?
And so on. How long does it take to put a twitter bootstrap page up? Like, 5 minutes.
How long does it take to...
You should be able to build an app that doesn't crash and does what you're trying to code in like a day.
You should be able to build something that is software you can launch with in like a week, as an MVP.
You should be able to replace someone else's mature product with a reimplementation in like a month.
You should be able to build a scalable business that is ready for a series A in like a year.
These things are not meant to be accurate, so much as show that you have imagination.
It's because estimates are really just a test of your imagination and skill. They're a "different game" from delivering something. Here are some examples:
How long does it take you to add 1 + 1 together? The only correct amount of time is "0 - no amount of time." But clearly that's not true, is it?
How long would it take you to multiply 5 by 7? Well, zero. No amount of time - you know it 'by heart'. It doesn't take you any amount of time to multiply 5 by seven. Well, clearly, that's not true is it?
How long would it take you to test whether 31337 is prime or not, by any means? Like, 1 second because Wolfram Alpha can tell me I bet. But clearly it wouldn't take me ONE second, would it?
How long would it take you to write a function to test whether an integer less than 2^32 is prime or not, without having to be super-efficient about it? Well like 10 seconds. But, clearly that's not true, is it?
And so on. How long does it take to put a twitter bootstrap page up? Like, 5 minutes.
How long does it take to...
You should be able to build an app that doesn't crash and does what you're trying to code in like a day.
You should be able to build something that is software you can launch with in like a week, as an MVP.
You should be able to replace someone else's mature product with a reimplementation in like a month.
You should be able to build a scalable business that is ready for a series A in like a year.
These things are not meant to be accurate, so much as show that you have imagination.