If I have a Will, probate is not required.

On the contrary, having a will often mandates probate.   When a person dies leaving a will, probate is frequently required to implement the provisions of that will and to transfer title.  Often, it is the only way for the beneficiaries to obtain legal ownership of property devised to them in a will.

A Will covers all my Assets.

A will does not cover assets held as joint tenants with right of survivorship, retirement plans, annuities, life insurance, financial accounts with payable on death or transfer on death designations.

I can write my own Estate Plan.

Estate planning is more than creating legal documents.  Comprehensive Estate Planning involves understanding the larger picture of how each legal document works in concert with other documents and with the assets at the time they are needed.

I don’t need an Estate Plan because I hold all my assets jointly with my spouse.

If this is your plan, your assets may be exposed to estate and gift taxes. Holding jointly owned assets will not avoid probate but will only delay it until the last owner’s death.  Additionally, assets may be subject to the creditors of all owners.