A story taking place over two days raises questions about burning through spells and other abilities. Seven years? Not a problem. Particularly if the characters are going up in level.
Even if you have a climatic battle. Running through spells is a checklist and lacks the kind of drama a story needs. The readers are not waiting to see whether the d20 turns up 1 or 20 -- or 7. You need a different sort of plot device to pull that off. Arising out of the chief flaw of the main character having to be overcome, ideally. A crafty use or abuse of a spell or a magical object that has been introduced before. At any rate, the decisive moment should be short because that's dramatic, and the long fight is feasible only as set up. Of course you might need to run through the spells to make it look bad for them. . . .
