After working part-time for the last five years, I have recently taken a full-time post. I'm only a few weeks in but my conclusion so far is that working full time is easier.
When I worked part time, I often had the same number of assignments as full time members of staff and was expected to use my own time. Additionally, on my days off nobody would pick up emergencies or phone calls/e-mails and so I'd have to wade through issues that had arisen on my days off and deal with them, before continuing with my existing work.
I'm now working full-time and I'm finding it so much easier. I'm keeping on top of telephone calls, e-mails and work, not having to work in my own time, having a lunch break AND still finding down-time isn't the week to have a moment to myself.
I'm remembering why I used to enjoy working so much. It's still early days so I could be wrong, but so far, things are much better.