I would say "very" based on the topic called Roleplay Builds I made in the spoilers forums. :tongue:
Not only that, but RP is the PRECISE reason that needing to rest is a good thing. A mage has great power, but it comes at the price of being squishy and needing to rest after casting spells. It's a pretty common theme in fantasy literature.
It would not be uncommon for me to exhaust a 300 point mana pool in about 5 game hours while wandering and exploring. Regenerating that pool takes 19 or 20 hours.
I know that a low level mage fails more often than a high level mage, but as I said in my example, i find it silly that I can and will deplete my mana supply Fighting a single bandit in a beginner cave. I agree with the idea behind what you are saying, I guess I am frustrated at how quickly you can and will spend you mana compared to how long it takes to resupply. [Breton Mage with Birth Sign: The Mage]
In Oblivion, regardless of mana regeneration, the spells were far more powerful... and in my opinion too powerful. You can simply walk up and use a fire bite to down a goblin, scamp, or highwayman in one hit. I would have liked to have seen some kind of middle ground.