[gjm11]

In other words, "natural family planning" achieves its very low "perfect use" failure rate by solving a different (and easier) problem from the ones addressed by other methods.

It's easy (in principle) to solve the problem of avoiding pregnancy: "just" avoid all sexual activity. The problem contraceptives were invented to address wasn't the problem of avoiding pregnancy but the problem of having sex without getting pregnant.

"Natural family planning" is -- when done optimally -- very effective at the "without getting pregnant" part of that, but not so good on the "having sex" part, since somewhere around half the time it's equivalent to abstinence.

Redefining the problem isn't always a bad thing, but it's as well to be aware of when it's being done.

[sp332]

That's fair as far as it goes. But you can mix NFP with other birth control methods to combine the advantages. Sex without condoms is valued by lots of people, so it's useful to know that even if you use condoms the rest of the time. On top of that, NFP can also help if you are trying to get pregnant.