For more than one shell buffer you can also do C-u M-x shell and then press enter (for the default buffer name) if you can live with shell-2, shell-3, etc. for

For more than one shell buffer you can also do C-u M-x shell and then press enter (for the default buffer name) if you can live with shell-2, shell-3, etc. for your shell buffers' names. Saves the time for renaming.