Liz,
There is no one-size-fits-all formula. No thing works the same way for all people, in all cases.
Pigeon (Exa Pada Rajakapotasana) is not a pose for delivering hip opening. It is a pose that requires hip opening. Of course once there is some opening in that movement of the student’s hip, yes there is also some opening provided. But this illustrates the difference between poses that offer hip opening and poses that require it.
The hips have eight movements. One of them is the nature of the hips for a being that stands erect and so that one is not worked at all. So there are basically six things worked in the seventh way (traction). It is best to find a teacher who knows these things and can impart them to you in a supine position to maintain the safety and integrity of your sacrum and lower back.
With the sequence we teach in Purna Yoga you can do it as much as you like, though I often do not expect students to do it more than twice per day. Right stuff, right thoughts, right living, effort, sound teacher, and patience!