The best place to look for efficacy data for drugs that have been studied in randomized trials, as has Radicava, is not on self-selected sites like PLM, which lack quality-controlled data.
Instead, it's wise to look at published reports of the randomized trials and their limitations, where you can get the benefit of multiple controlled trials and better understand who exactly was studied.
I have attached a backgrounder/roundtable with some well-known ALS clinicians. It certainly highlights that from what we know, starting it early as possible would be desirable, if you are going to try it.
From the available data, if you start it later and/or when you are more disabled than the patients in the trials, some slowing of progression is possible but you will have to take it quite a while before your results could be different than if you had not taken it at all.
Of course, not everyone will live that long, or want to. So if started in mid-late disease, it is more of a kitchen sink than likely to make a real difference.