I would think that, at least in some cases, stopping treatment isn't as much a "halting" of treatment, but more like a "finishing" of it.

I know in my case once i'm rid of T-producing organs, I plan on stopping my related meds. And once I've achieved all the feminization Estrogen injections can provide, I'll no longer be taking it for any transitional purpose. (Likely just going to be whatever level feels right for emotional/mental support, which I'd argue isn't in most peoples concept of transition treatment.)