Building a container shouldn't be any longer than it takes you to ssh into a production box and convince yourself that the code you just changed isn't broken.

Building a container shouldn't be any longer than it takes you to ssh into a production box and convince yourself that the code you just changed isn't broken. Keep image size as small as possible (reasonably) and optimize your images to that the things that change the most (code and config usually) as the last layer to take advantage of caching things that don't change often.