It depends how well you manage you time, quite frankly.
There are part-time agents in my office that run circles around some of the full-time agents in terms of production and income. As Mack correctly states - it depends what they are doing with the rest of their time.
My 1st year in real estate, I worked part-time as a buyer's agent. I was told to save my money because I wouldn't sell anything for a least 6 months, and maybe not at all since I was part-time. I went on to sell over 3 million dollars or residential real estate and outproduced many of the full-time agents who have been in the business for 15-20 years. Not a huge number - but I was happy with it being my very first year. I found that there are still a large number of agents who are working harder, not smarter - and stuck in the same practices that, while effective 20 years ago, aren't necessarily effective or efficient now.
In real estate, most agents are going to try and use their years of experience, and production against the agents that don't have as much. The full timers are going to tell you that they are going to service you better than the part timers. The teams are going to tell you that they can service you better than the full timers. The top producers are going to tell you that they can service you better than the "medium" producers...etc. etc. etc.
At the end of the day, ask prospective agents the right questions - and choose one that is the best fit for you. Whether full, part-time, or the head of a "team" - ask for references and get a 1st hand account of how they conduct business. If you aren't getting the level of responsiveness you demand from your agent, and not getting your questions answered correctly - it's time to find a new agent who will service you better.