Master is the only way to get any challenge at all, once your character levels up a bit...
And it's still too easy.
Plus I use "Resilient Dragons" and "Higher Level Enemies" mods.
Got jumped by four Draugr Deathlord Demigods last week, and I died!
(First time since, I dunno, Christmas maybe)
I find there are two "plateaus" that are reached playing the game:
First - once you can smith enchanted items. Instant upgrade from Adept to Expert (unless you like it too easy).
Second - once you can double-enchant items. Instant upgrade from Expert to Master.
I mean, if you are wearing a ring that protects against both fire and frost, how scared of dragons do you need to be?
Not very.
That's why Resilient Dragons have thousands of health, and Shout at you like crazy...
Fun!
Adept or expert. Never saw the need to go higher.
This is like saying "I have reached Level 20. Never saw the need to go higher"...?