As long as the massage is good and not stressful (meaning insensitive or brutal) there is no reason why not to get daily massages. In fact there are plenty of destination spas where clients stay for extended periods of time, and all they do is go from one treatment to the other, all day long, every day.

Most of those studies are done on people with conditions. The studies help determine at what point massage has optimal effectiveness, and at what point it stops contributing to the healing process. As long as you have no contraindications, and your therapist is working within your comfort zone, you're good to go.

the general answer is no. that said, everyone has different conditions, external and internal. the real answer is that "it depends". I know that's not what you are looking for, but the reality is that everyone needs to listen to their body. massage is such a thing that you don't need to guess. you simply listen to your body and you will get the answer right away.