Are your headaches worse when you're upright and feel easier when you lay down? If so they could be down to low pressure. The lumbar punctures are usually done when your doctor feels that you need to have one if he thinks that your pressure needs to be decreased because it is too high. I don't think it is dangerous to have them regularly, but it does over time affect your back because of the scarring lefty behind.
Before my shunts, when I was on Diamox there were times when I had them in multiples of 2 or 3 within several weeks of each other.