Surely part of the discrepancy in timing is indirectly linked to "importance", since we typically include "lethality" and similar measures into what we consider

Surely part of the discrepancy in timing is indirectly linked to "importance", since we typically include "lethality" and similar measures into what we consider important. Clearly a good chunk of the time spent in trial is to determine side-effects, contraindications and the like. Given that more "important" targets are also likely more "lethal" targets, then their bars for acceptable side-effects are surely going to be lower. I mean, who really cares if there's a potential for 5% of drug takers go blind, if the increase in survival rate over the current best option is sufficiently high.