[lars512]

I find the opposite. Installing a useful module for a once-off task is a no brainer, since I won't have to worry about whether I'm introducing some long-term dependency I'll have to maintain.

The real issue is in discovering that a better option exists in the first place.

[100k]

And then you have to deploy it to the server or someone else's computer and it sucks.

[lloeki]

pip freeze works even without virtualenv. Expunge things you know don't matter, and send to third party/deploy, which then just has to run pip install -r requirements.txt.