Though it is the easiest for small farms, you do not have to always install jobtypes locally on the Workers. They can be centrally located on a network file system.
Set the worker_template_path to point to the location of the jobtypes (delimited by colons on OS X / Linux and semi-colons on Windows), but ensure you also include the default worker_template_path, as this contains the compiled 'cmdline' and 'cmdrange' jobtypes that are installed with the worker.
Examples
Windows
worker_template_path="C:/Program Files/pfx/qube/types;C:/Program Files/pfx/jobtypes;C:/Program Files (x86)/pfx/jobtypes;//server/share/qube/ourJobTypes"
OS X
worker_template_path='/Applications/pfx/qube/types:/Applications/pfx/jobtypes:/mnt/nfsPath/jobtypes'
Linux
worker_template_path='/usr/local/pfx/qube/types:/usr/local/pfx/jobtypes:/mnt/nfsPath/jobtypes'