A lot depends on how you handle magic in the first place.
If you do mana types, Fixed mana use should work as long as you have components, unless you rule that the area drains the magic from them. Personal mana would work until the caster runs out of points, but then the caster could not regain mana within the area. Granted mana would work so long as the caster still has the support of their God. Ambient mana would not work at all.
On the other end of the scale there are more options. Again, I would think Granted mana use would remain largely unchanged. For the rest, well... what do you think the result would be of a saturation of mana? Would spells have random additional scaling? Would you have to worry about components catching fire? Would you have random Fortean effects? Would casters be forced to keep casting spells in order to avoid overload and mental damage of some sort from the resulting burnout?
There are any number of ways you can handle it, and for many of them, the result would be casters thinking, "Wow, this is really cool!... wait, what? Aw man, this sucks!"