The quick and dirty jobs that we all do every now and then.
These times are when you need automated testing the most.
I don't really need automated testing tools when I write a small program that I just use myself for some task.
If it works it works, if it doesn't I do it again.
Yeah many times when you are 'spiking' and idea you can work through a simple small example fastest without testing. I agree when you are quickly just trying to see if something is possible testing will slow you down, and isn't worth the benefits of TDD.
Then when I start to integrate that solution into real production code I go back and add some tests. (mostly integration tests)