If you use a certain ritual that the client learns to associate with getting results, feeling better, or with the professional skill of the facilitator, then it has a certain suggestive value. The facilitator can be less meticulous in convincing the client that the session will work, and can rely more on the ritual convincing the client. So, even if the facilitator has a bad day and isn't particularly doing anything very smart, the client can still get good results based on the presence of elements she recognizes that are associated with good results in her mind.
The reason I am spelling this out so brutally is so you don't fall into the trap of delivering only ritual. Some practitioners might try to practice a rote, mechanical delivery or a pre-written script. That might work well for a while, if the script is written well enough. But there is really no comparison with a session where the facilitator is really there and is dealing with the actual client who is there. The results from sessions that are only ritual will tend to wear thin in the long run. The client might after a few years realize that nobody ever really listened to her, and she still has her major issues intact.
What I am proposing is to use any suggestion and ritual knowingly and sparingly. Know what you are doing, and observe the effect it has on the client. Change what you are doing if it is no longer useful in giving the client more freedom.
There is a considerable advantage in keeping sessions with a certain client within the same setting. Preferably use the same room every time, or at least a very similar room. Give the client the same chair and sit in the same chair yourself. Keep the environment fairly constant.
It also makes things easier to use a recognizable pattern for how sessions are started and ended. You don't have to say the same words, but you might want to do the same type of action. It might be as simple as session starting when you sit down in your chair, and ending when you stand up. There doesn't have to be any words to it.
There is nothing wrong either with making some of the processes done somewhat ritualistic. It might make both the facilitator and client more comfortable by doing something that is familiar. It should not be overdone, though.
What must be thoroughly avoided is that the facilitator becomes a robot with predictable behavior based on certain actions from the client. The facilitator must remain in control of the session, maintaining greater flexibility than the client. If the client finds herself in control of the session much of the magic is gone and she is left without anybody there to help her.
So, the rituals of what is being said and done are used to give a familiar framework for a session. They should not be used to replace the presence of a facilitator.