So far as I can tell, the i before e rule works in every case where the ie or ei is pronounced ee. At least, I can't think of any exceptions.
Might pet hate, which occurs all too commonly in speech also, is could of/would of.
Could've -> Could have
Would've -> Would have
Might pet hate, which occurs all too commonly in speech also, is could of/would of.
Could've -> Could have
Would've -> Would have