Research and experience suggest that usually weekly sessions are ideal for a client to meet their goals. Time and cost limitations can be relieved by stepping down to alternate weekly sessions. If motivated, journaling, reading, or homework may fill the gap between sessions so as not to lose momentum. Even in these situations, I have seen best results when the client starts the first few sessions by attending weekly to establish a therapeutic relationship, and then stepping down to alternating weeks.
Less frequent than alternating week sessions can become problematic. We end up spending more time getting caught up on events since the last session than making progress on your goals. Times when less frequent attendance works is when tapering off counseling once goals are met, to make sure progress is maintained instead of sliding into old patterns and habits. Also, occasional check in sessions when on a sabbatical from counseling can help stay connected with the counseling process until ready to return to progress.