Therapy lasts however long you want. "Gee, thanks, Lee. That really helps." Seriously, it's important to know that you're in charge of how long you do therapy for. You can quit or slow down anytime.
When To Do Therapy
I think it's smart to do therapy when you're especially motivated to change--because that's when you will change--and to quit or pause when you're more in the mood for just cruising along, using the stuff you've learned in therapy. You can always start again if you get motivated again by desire for change or by discomfort with what's going on. Don't stay in therapy if it starts to drag...or, at least tell your therapist, "This is starting to drag. Let's look at why it doesn't feel as helpful to me anymore."
How Much Therapy Is Best For You?
I wish I could give a simple, across-the-board answer, but it varies massively. Someone who needs help stopping smoking might do 1-3 sessions, and someone who needs to heal from incest and terrible self-esteem might do therapy for years and still be getting good help all that time.
If you're trying to estimate how many sessions might be practical for you, think about these factors:
* How long-standing is the concern? Longer tends to take longer to undo.
* How deep do you think it goes? From the examples above: smoking likely isn't a core part of your psychological makeup (so, likely faster to deal with), whereas incest throughout your formative years plus very low self-esteem cuts very, very deep, to the core of one's identity, sense of safety, views of relationships, etc...so that's likely to be some long work.
When To End Therapy
* When you lose your focus / motivation / curiosity for it. You can always pick it up again later if you want.
* When you don't feel safe with your therapist. (Do take a minute to think through whether this is natural reaction to some difficult work you're doing together vs. this therapist really isn't safe--in which case, bolt!)
How To End Therapy
No rules here, but some ideas:
* Tell your therapist as soon as you know, so they can help you get the most out of the ending. If you're ending in the same session, there may be things they could suggest that they would've otherwise gotten around to in a later session.
* Review what you've worked on and what you've learned. It's very helpful to review this stuff to confirm it (over and over!).
* Share ideas about how you can keep the progress going after therapy.
* Think about whether there's anything you would wish you had said to or asked of your therapist...now's the time to say/ask it.
Remember that it's okay to come back later. No one finishes healing and growing, so returning to therapy--whether for a session or a long haul--doesn't mean you've failed; it just means you're ready to do some positive work again.
Licensed psychologist, Austin