I suspect non-elites who follow a Daniels-style approach probably train at a variety of paces too, although not always intentionally, and not across the entire training cycle.
I follow a Daniels-style approach, and as a practical matter, I regularly hit on mile/3k/5k/10k/15k/half-marathon/marathon paces, with 3k and marathon pace being the least frequently touched on.
The mile stuff is straight Daniels rep work, and as a practical matter I usually end up a bit faster than actual mile pace to mile pace during a workout.
The 3k/5k paced work is straight vo2max work. I usually pick my most recent 5k road race and use that as the basis for my workouts, but I inevitably end up a little fast when I do them on the track, and come near 3k pace from time to time (which is okay in a Daniels style world as my true vo2max pace is somewhere between 3k and 5k pace).
The 10k paced work usually comes in one of two ways: by touching on it for a mile or so during a progression run (a viable way of getting threshold work in for a Daniels-style runner) or via doing cruise intervals on the track in lieu of a straight tempo run, with the latter usually being unintentional and, from a die-hard Daniels perspective, undesirable. But, as a practical matter, I suspect that this outcome is pretty common.
The 15k/half marathon stuff is pretty much straight T pace, so no explanation needed there.
The M pace work comes either in the form of a long tempo run or as part of a progression. For me, it is usually part of a progression unless my goal race is a marathon.
On top of that, during my base phase, I will often run at some pace in between classic easy distance pace and marathon pace, if I am just feeling good.
So I think we like to put things in boxes that they don't always fit into. While it is true that the vast bulk of my quality days will be done at threshold or vo2max pace, I definitely touch other paces, with some of those touches coming fairly regularly.
The reason I don't intentionally try to touch on those paces more is that I only have so many quality miles in me each week, so while running at 5:10 pace may have some value despite being between my vo2max and threshold paces, I feel like if I am only going to run 7 or 8 miles per week as workout miles, I want to do them at a pace that is most likely to get the most bang for my buck, and to let the "in between" paces come as they will (which happened to me this weekend when I ran one of my miles in my 3 x 2 mile workout at that 5:10 pace).