The remedies are loosing their effectiveness when the body is getting used with them. Like eating something you like very much but in time you are getting used to it and you don't like it as at the first bite.
Sometimes, the simillimum for a situation is in a particular dilution and it determin a change when it's a good dilution and frecvency in administration.
Also, it's a 'quantity' of need of the body to that remedy. Let's say it's like a cup which can be filled...
In my oppinion, the cure is possible with homeopathy help (if the person is changing - usually, the remedy is the trigger for the change).
We are living as an opened system, so, everytime we interact with something or someonelse, and we don't find a good way to adapt, we begin to disorganise ourselves and finally, we need new remedies
In conclusion, take right remedies only when you need them.