tecnowraith said:
let me try to re-ask the question. For an average adventure day, how many spells are from class and/or scrolls?
I seem to recall the DMG stating that there is a four-encounter-per-day estimation taken into account when determining Challenge Rating as well as other general mechanic balance. I cannot seem to find this quote, however.
Extrapolating from this, we can see that the number of spells cast/items used in the average adventure day is dependant on the types of encounters the given party experiences and how they utilize their abilities in said encounters. If the wizard is wont on desruction, she could memorize nothing but destructive spells and blow through them all in a single encounter, if not used wisely. It is entirely dependant on the situation.
However, I can assert a brief generalization from my own experience:
Lower levels: 3/4 of spell slots per day
Mid-levels: 1/2 of spell slots per day
High levels: 1/4 of spell slots per day
Items are far more difficult to estimate. Again, it depends on how often the DM hands them out as random treasure, how much down-time the party has for the creation of such things, or the existence of a merchant that deals in items of power. Far too vague a question.
Either way...just my 2 cp