I agree it really depends on what you are trying to achieve. It can take sometime to source the right person to do the job. I disagree that you should only outsource to a freelancer if you have a one off project. My designer is a freelancer and I have been using her for several years because I like her style and she is very fast and efficient so I end up paying a lot less for the work and there is usually very few edits.

I think that for any business it is worthwhile investing in creating a good relationship with any member of your team. If the work you required isn't a full time role, then hiring a freelancer makes a lot of sense because you can build a loyal and trusting relationship with them and therefore depend on them to deliver.