Haven't got the chance to reply to this thread until now but I love this topic!
There's something to be said about stacking layers for "feeling" rather than to be at the forefront of a mix, or to fill up space and create a huge wall of sound, but IMO it's an amateurish move to just stack a huge amount of layers to fill up space instead of making sure that you have the right sounds to work with at the beginning, and judiciously using EQ, level balancing, reverb and delay. Uplifting trance from about 2009-2015 really overused the wall of sound IMO, and while I think there were still a lot of great tunes that came out of that style (such as
Napalm Poet; a true modern classic
@adamellis), there were also all the Andy Blueman copycats and such
who would stack an obscene amount of layers to the point that the climax of their tracks had nothing clear. That's the problem with walls of sound - nothing is distinct and everything is just soup. Doesn't mean it doesn't have a place - the climax of my own track
Wild and Free (which had a maximum of 33 channels in the Ableton file) was consciously aiming for that to give it emotional power - but it shouldn't be a side effect of bad mixing decisions.
The best trance, IMO, uses as many layers as is strictly necessary - and that doesn't necessarily equate to the number of channels. Back in the "golden age" of 97-04, DAWs and VSTs were still primitive, so unless you had a studio full of a lot of expensive hardware you were making tracks that had a lot fewer layers on average, and so had to make every one of them count. A track like
Airwave's Ladyblue probably only has about 15 layers max, but they all have a place in the mix and it still sounds huge and spacious all these years later. (On that note: I'm guessing the fact that Laurent had to perfect his sound using limited hardware meant that he knew much better how to mix the very dense and multilayered stuff he made after 2012, which was leagues above the other dense stuff being made at the time; although
even that got too full after a while, and he's since dialled it back on his more recent work).
Here are some tracks that I think exemplify the idea of using a smaller amount of layers for maximum impact:
^as I recall, Orkidea intentionally made that track with as few layers as possible as a challenge to himself, and it still works very well
^this track probably has between 50 and 100 channels just for all the one shot synth hits and FX, but it still has a lot of space even in the climax. The synths do most of the work to fill up the mix without needing to layer them too much.