This may be controversial, but I think challenge rating has been missold. I might even go so far as to call it a dangerous myth.
Is challenge rating a lost cause?
Amazing advice from the 3rd edition DMG
I know it’s not a particularly glamorous topic, but the rhythm of the adventuring day is key for establishing an appropriate sense of threat. If encounters are too easy, the game feels trivial; too hard, and every combat becomes a slog. Get the ratios right, and the players feel like badass heroes.
Site-based adventures, or how I learned to stop worrying and love the dungeon
Are site-based adventures going out of style? If you think dungeons are unimaginative, repetitive slogs that only reward combat – read on!