Well the good news is that by the three month mark, you essentially have a clear understanding of how you are reacting to any SSRI. I think he will definitely be able to see how S&A augments his new baseline...whatever that is.
It is unfortunate timing that he was not able to try S&A first, as I don’t think any of us like to be “dependent” on medications. They don’t have to be a forever thing though, and people get weaned off them all the time. Under medical supervision of course
Other times, people feel like they just stop working or they develop a bothersome side effect and switch to a different one. I originally stopped Paxil only because I developed bruxism that was quite problematic. Otherwise, it was awesome! Not long after stopping that is when I went through everything under the sun- at that time. Also, I kind of wanted to try them all so I would know I was taking what got along with me the best.