There is an alternative if the higher levels are an issue. A lot of the balance issues at high levels have to do with the actual levels. Such as spells and abilities the players have access to.
You can actually dodge a lot of these issues and still have the same "plot lines" and enemies. You can do this by subbing in magic items for levels. The math in 5e is predictable and elegant with almost everything based on proficiency bonus and ability modifiers.
Knowledge of this same math, how everything from DC to "to hit," is based on the same 6 numbers, also benefits encounter design and balance.
So what I've started doing is just not playing at high levels per say. But raising the power of the magic items I give to compensate. Watching a entertaining combat between level 12s and a CR 24 is weird in some ways. But those level 12s are level 20 in power due to the items I gave them.
I hope this is a helpful Idea for someone

. I've found it's almost a game changer for me.