As with all things bbq, there is no right or wrong. Do what feels good. I have never thought basting, or spritzing for that matter, does anything for the moistness of the meat but as mentioned above, it does have an impact on color. I don't do it much but sometimes I just can't help it.
You should consider the turkey you are cooking. Many, such as Butterball are pre-basted and basting them might even be counter productive.
I have a butterball 12# and my plans are to simply coat it with a bit of Olive oil before I start it spinning on the rotisserie in my Genesis 1000. Oh, and I will be using a bit of apple wood for smoke.