How do you determine those percentages? The reason all these studies are necessary is because biology is hard. Example: cancers where Ras proteins are mutated

How do you determine those percentages? The reason all these studies are necessary is because biology is hard. Example: cancers where Ras proteins are mutated are common and also predictive of poorer outcomes. Ras signals through several effector pathways including ones involving BRAF. So if someone develops a BRAF inhibitor, we should call it a day and people should just start taking these? Ooops, turns out this paradoxically enhances Ras oncogenic signaling.. Is it better to find that out 6 months when everyone who's taken these dies, or would these people be better served by doing your beta testing and "years of studies/paperwork" in cancer cell lines and mice?