"An interesting point here is that isolated studies show the opposite : the “effect” of continuous effort vs. intervals in isolation seems greater. However, this is missing an important point : the limiting factor in terms of load comes (mostly) down to the muscular system in running. So you need to weigh the session effect vs. the actual load and try to fill as much as possible of the “correct” training while balancing the muscular system."
I read this as saying that continuous sessions yield greater adaptation than equivalent interval sessions. To me, that suggests you should actually be doing continuous sessions until you're at a volume/intensity of training where muscular load is your limiting factor. Beginner runners, lower mileage runners, and anyone who takes multiple days between harder workout efforts would therefore seem to benefit more from continuous over interval threshold sessions since their muscular systems are likely well recovered before they are attempting the next workout.
In fact, taking this a bit further, you should only incorporate more intervals (including doubling) once you are at a level where you need to optimize around muscular system recovery rather than around building up to more threshold volume.