I'm a PHP developer who uses drupal whenever the job looks like it could benefit from a CMS. I was having a discussion with a colleague who said that it helps him a lot with clients that he knows multiple content management systems. To me, this sounds like dividing one's efforts, and I'm not sure if it's worth it to invest the time learning another content management system.
Is it often that jobs lend themselves better to one content management system over another? or can most content management systems handle most jobs?