Must a person with a will go through probate?

Whether a person dies having executed a will or not is completely irrelevant to the question of whether a decedent's probate estate needs to be instituted. As you likely know, a will is a document that directs the disposition of a decedent's assets following his or her death. A will can only effect assets that are held in the decedent's name alone. A will has no effect on assets for which there is a surviving joint tenancy owner or where there is a living named beneficiary. And so, almost by definition, a will can only effect probate assets. People are sometimes under the erroneous impression that because a person has a will, no probate proceedings are necessary when that person dies.

The presence or absence of a will is completely irrelevant to the question of whether probate proceedings will be necessary upon a person's death. The question of whether or not a probate needs to be instituted can only be answered by answering the following:

What assets did the decedent own an interest in, how were they titled and what were they worth?