At my company we build with Jenkins, tarball it and deploy from that. I haven't had experience another way but I think it ends up being more efficient and less error-prone than doing actual pip installs during deployment.
That's basically what the company I used to work for did as well with our large python application. Build using a build script, pulling in dependencies from local build server, test, package up the result and deploy. Pip was used for pulling in libraries to the build machine and never used during deployment.