Well, my perspective is a bit different. We have been married, going on 10 years now, and we have never really used NFP (and certainly not any form of birth control!!) We are 5 months along with our 7th child. (11th pregnancy). We began to learn the ‘method’ through CCLI, and a month into the class, we knew God was calling us really and truely give it all to Him. (this was w/in 3 months after our first child was born, and we were experiencing the normal infertility that can come along with breastfeeding)
It has been so beautiful and so liberating. We were no longer answering to thermometers, charts, and cervical mucus, and became so much more in tune to each others needs and to the voice of the Holy Spirit in our marriage.
I completely agree and will attest to the fact that period of abstinence are good for a marrige. We have many times prayerfully chosen periods of abstinence, that did not revolve around my fertile/infertile times, for specific intentions. These periods are then purely for those intentions, and not the added intention of avoiding conception. We do not know how to use it well enough to achieve or avoid a pregnancy. If we did face some grave or serious reason to post-pone another child, we would abstain altogether either until our circumstances changed, or until we did learn the method well enough. (and maybe in that time our circumstances would change anyway.) *I also wanted to add that, there are more than enough periods of abstinence when you have many little children running around!
I am not at all saying that NFP is wrong, or that it does not have it’s place. I do believe it to be over used and over promoted. The couple that taught the one class we attended, though CCLI, boasted that the method worked so well, that they had the three kids they wanted, when they wanted them. That really bothered us.