Cathy Liska 
The average coaching relationship lasts one year. Some coaching relationships are just a few sessions and others continue for several years. For internal coaching programs, in the program manual provide parameters for the length of the coaching engagement.
Often a minimum time period makes sense because this creates and supports commitment to the process. Additionally, coaching is a process and creating meaningful change takes time.
Ultimately it is important that the coaching is providing value. Whether just getting started or after a period of time, the key consideration in whether to continue is the benefit the coachee is gaining from the coaching relationship. The International Coaching Federation, ICF, Code of Ethics addresses this specifically in Section 3:
19) I will respect the client’s right to terminate the coaching relationship at any point during the process, subject to the provisions of the agreement or contract. I will be alert to indications that the client is no longer benefiting from our coaching relationship.
20) I will encourage the client or sponsor to make a change if I believe the client or sponsor would be better served by another coach or by another resource.
21) I will suggest my client seek the services of other professionals when deemed necessary or appropriate.
In an organization with a coaching program, often there is a goal of creating a coaching culture. This means coaching is happening informally and coaching skills are applied in conversations generally. Scheduled coaching sessions make sense when the coach and the coachee are both aware that the process is providing value. The coaching relationship continues only while the coachee is benefitting.
