The majority of people going to therapy average three sessions a month. Their focus is to go every week (4 sessions a month), but life isn’t always easy to work with. Sickness, work obligations, family, and overall exhaustion, are a few of the reasons that only 3/4 of sessions happen each month.
To get the most out of your therapy sessions and investment of money paying for them, you want to go once a week for the first 3-6 months.
If four sessions a week is not something you can do because of time or money, then go three or two times a month.
I do not suggest going one time a month to therapy, especially if you have never gone before. With only going to one therapy session each month, you and your therapist will have a hard time getting settled into any work due to the vast amount of days between each session.