We can actually reduce the number of mechanics by taking previous mechanics and adding LAYERS to them (oh dear god here's my autism)
Ultra Custom Night is a great example of this: there's 5 flashlights that are under the same bind
You can also add door addons that affect only certain characters to futher raise this number of mechanics
UltraCN also has floors that allow more characters to be on levels at the same time
They've added 700 characters, take a look: https://ultra-custom-night.fandom.com/wiki/Ultra_Custom_Night_Wiki