It depends on what you mean by "working." When you use a remedy according to the law of similars that matches the disease in the patient, you have a curative action. It can take time to work through layers of disease that can go very deep.
So the treatment can be curative according to principle, yet the patient might not always get the relief of symptoms that they expect, or not in the timeframe hoped for. The life force of the patient has to be up for the task of healing, which we call the counter-action to the curative action of the remedy. So in some cases the success of treatment in terms of symptom relief, especially in older people, can be limited.
In many cases, though, symptoms can resolve, or at least the treatment can be very supportive and help the person to handle the situation more calmly.