A lot ofunknowns in this statement, although an exact breakdown of the specifics and metrics of these schedules would be interesting. But how easy is easy? For instance someone in this thread was once saying they did 4 easy runs a week, a workout and a long run with quality in and had good success.
But when you look into it, the easy runs were really quite hard (75-80% MHR) he workout was almost 35-40 mins of quality and the long run was probably an hour above Lt1 with about 3-4km either side. Not saying this is the case here, but the person about a year ago in this thread who had good success like that, was probably actually running more intense than something like NSM over 6 days. So it shows you unless you really have an idea of exactly what someone means when they give an outline of a schedule, it can seem easier on paper than it is.
Personally from my point of view, having ran many few different ways over the years, It's significantly easier to run 7 days a week, with 30 mins of Subthreshold three times a week than just about any combo of training I have ever tried. I'm getting older as well, so you would think if anyting this would be making things worse, if 3 controlled workouts a week were a problem, I'd be feeling it even more these days. That's just my view but it seems to be a wide range of people saying the same thing. I think there is something in spreading everything over 7 days there is actually a big advantage to, if time or lifestyle allows.