How often do people with wavy hair get straightening treatments?

My hair isn't completely curly, but the baby hairs grow out curly.

If I don't straighten my hair, it gets all puffy and frizzy all over, so I feel like I have no choice but to get it done...

Hair salons are so expensive these days, and straightening treatments are really pricey too, but...

When I do it myself, it feels a bit calmer for about a week, but after that, it seems to be the same...

Do you usually have your period about once every six months?