An unreliable software development cycle estimate-why is the development cycle always estimated 2~3 times? Do you understand?

Question: Why is the software development cycle always estimated 2~3 times? Is this the developer's fault? Or a management problem? Technical rough, or some other reason? Or it's just a procedural law of the ape World ...

Let's go from San Francisco and hike along the west Coast to Newport Beach in Los Angeles! Look at the map and plan the route. Route Map

Well, the Red Brigade was about 400 miles (643.7 kilometers) away, the men slept 8 hours a day, ate 2 hours, teased the cat for 2 hours, and could walk for 10 hours, and walk 40 miles (64.3 kilometers) a day.

So, 10 days after the night six o'clock, we will be able to roll to Los Angeles, hurriedly let L.A. friends booked this weekend's dinner, think all excited Ah!

The next day, everyone gathered in the morning, back good bags, spread out the map, planning the first day of the journey ... Well? The first big picture

It looks like there's a lot of twists ahead. 40 miles is only half way to the Moon Bay. The whole journey was not 400 miles, but 500 miles. Call L.A. quickly, postpone dinner time, must be realistic. Although the base friend is a little disappointed, but still eagerly look forward to our arrival.

Say 10 days to 12 days, it seems no big deal, with the first day of small frustration, we finally set out. 2 hours later, we finally walked through the zoo near our home and looked down the path: the path

Dear brothers, This is a snail mode! Sand, waterways, steep ladders, ground fissures, angry sea lions ... Our speed is 2 miles per hour, only half of the planned speed, do we have to walk 20 hours a day? Let the base friend postpone the dinner date again.

In this way, we have an agile strategy: we don't tease cats on the road, we walk 12 hours a day, and then we ask the base friend to postpone the dinner date to the next weekend. L.A. is a little hairy, but it's done.

After 12 hours of walking, we're going to bury the Shing in Morse's beach. Damn it! There's never a decent tent in such a gale! Last night to lie down, no big deal, we are Westeros Tiemin, tomorrow to go faster on the line.

We overslept and rolled around until 10 o'clock. Times Oh! How can you walk 12 hours a day? Come on, let's go for 10 hours today and take 14 more hours tomorrow.

After a few hours of hard spell, I found my teammate limping. Oh ~ I bought a watch last year, a blister on my feet! Must be dealt with immediately, the problem is nipped in the cradle, we are a team!

I ran for 45 minutes, 3 miles, bought Bundy for my teammates, I was tired, and the sun was coming down the hill. This day is basically reimbursed, we only walked 6 miles. But I bought a new supply, the situation is OK, tomorrow will be better!

After getting up, we went on the road with bandages. The front of the enlightened ... Time Oh time oh oh, what is this? Cliff

There's no picture of this place on the map! A cliff let us fly, we had to bypass the inland, walked 3 miles, lost two times, noon to return to the road.

This half a day is only 1 miles away. Will you call L.A. again? No way!! We must stay up late so that we can catch up with the schedule.

After a night of difficulty, the teammate woke up in the morning with a headache and a high fever. I'm going to give him a pep talk and keep him going, and then he's hairy, "Bastard!" I have been walking in the freezing fog for 3 days without a break. ”

Well, today it's gone, let's fix it. After trimming, we must go 14 miles a day! Because we have been accustomed to, not a few days, we insist on the line.

Waking up trembling in the morning, forcing myself to look at the map:

Son of a bitch!! We walked for 5 days before we left so little! Must be done to carefully estimate the distance, summoned all the teammates meeting, not awake to yell at me, everyone must face the reality again.

The teammate said: "We have 4 days to walk 40 miles, there are 600 miles, so it should be 60 days, conservative point of estimate, 70 days." ”

I broke down: 70 you big ye! Well, although I have no experience with this kind of travel, how could it take 70 days to get from San Francisco to Los Angeles!! What do you want me to say to L.A., to meet again on Easter? ”

I went on to say: "If you can walk 16 hours a day, things will be completely different!" Although this is a pain in the egg, but now is a critical moment, let us go!! ”

Team-mates yelled at me and came back: "I didn't tell L.A. we could walk in a week, it's your duty to kill us." ”

Big Silence ~ ~ ~

The last call still didn't hit, and I'll talk to him again tomorrow after my teammates get back to their senses.

The next morning, pouring rain, we hid in the tent to 10 points before packing. With sore muscles and new blisters. I didn't want to mention the quarrel last night until I found out that my teammate had left the kettle! I t-m-d kill you, we can only take 30 minutes to walk back to find the kettle.

I suddenly had a flash: Hey! We ran out of toilet paper! We have to get to the next town to replenish the ammo. But, the front is suddenly enlightened, roar of the CHA in front of Pentium, and I small belly sank, chrysanthemum a tight, just want to poop ...