I'm doing it part-time currently but I'm running other things too. However i would suggest to do it part-time unless you can work efficiently and have "enough" work for a day. According to my experience, doing IM full-time require great productivity,I sometimes spend my time outside home and found that I can produce the same amount of productivity when I'm home all day. :boff:
So doing full time only if you have a lot of sites or thing to work with all the time, however sometimes you might feel that the workload is unlimited but it may actually not if you have daily checklist and good time management, it's all about productivity.
So i usually procrastinate a lot during the day, thus my productivity is not really higher than when i do something else together. But in contradict you will have more free time to surf internet, play online game or have a meal with your family.
For example, if you run a website, you would feel that you can work forever, but actually you can manage to work in few hours then leave it to do something else.
Maybe
-Upload an article
-Share it on social networks
-Finish excel for workers to make link according to assignment
-Post comment on neighbor blog to get daily link juice and relationship
-Edit 2 old article, update some information to refresh them.
-Find 2 long-tail keywords for next week article building.
This could be an exam of workload in a day (for blog owner) If you're running something else it may take less or more time. You can see that this can actually be finished in 3 hours or less, but some people including me might spend a whole day due to being unproductive.