Python is actually one of the things I've found it to be great with, you can for example have all your "command" recipes depend on the virtualenv directory, and

Python is actually one of the things I've found it to be great with, you can for example have all your "command" recipes depend on the virtualenv directory, and the virtualenv directory depend on your requirements / lock file. That way you don't have to worry about keeping the virtualenv up-to-date, it'll automatically do so any time the requirements file changes next time you try to do something, and it'll skip that step entirely if nothing changed. The only downside is that the last part requires a small addition, the install doesn't change the virtualenv dir's last-modified, so that recipe has to end with "touch $@".