I'd adjust my unit settings to my enemies, but not my strategies.
You'd be surprised how often the same armies re-use the same unit settings for every single battle. If you know how the enemy will deploy, you can use it against him.
I sometimes make the mistake of keeping my settings the same for too long, although that's also getting less and less so.
I do adjust my strategy however, I find it useful from time to time. Mostly on the entire context however and not just my enemy.
