Sometimes even for a one-shot job you dive down and write passable code then as you start to tackle the complexities of the problem at hand you realise that the amount of ropy code has just tied your hands and now it gets increasingly harder to wrap your head around your implementation and finally complete the one-shot job.
It usually starts with "oh it's just a one-off thing" and then it turns out to be useful and the rest is messy history.
But sure, within that genre I could see Python being a faster language to write in than many others.