It's OK if this happens once.

But having worked behind the scenes, if your site is down for half a day it means a huge amount of stress for some poor suckers.

I applied to OKCupid to work back in the day and never heard back from them - my resumé emphasize how important I find testing.

I love testing because it means I don't get woken up in the middle of the night with a panicked phone call, but also because it means I can write code a lot faster.

I can make even dramatic changes quite fast because I can divide them into small, incremental changes, each of which preserves existing tests and has new tests.

Sometimes for some plum new feature, I need to make changes to some fundamental data structure that touches anything. Before automated testing, this required stopping for an hour to test everything by hand. Now I can make huge changes and run my tests, and have confidence I have broken nothing.