It probably depends on what the cause is, so the FS might order some hormone blood tests and then treat accordingly. The first line of treatment for me was Clomid to regulate the follicular phase and ovulation and then progesterone pessaries to lengthen the luteal phase.

Natural treatment options from the naturopath was vitex. This worked for one cycle but then I started seeing a FS and was prescribed the above treatment so I don't know whether vitex was a coincidence of would have fixed it over the longer term.