I engaged a lawyer experienced in packages to negotiate my package. I had asked my contacts to recommend a good lawyer in this area. Fee based, not contingency.
My goal was to have the package enhanced and to have the T's & C's of the agreement reviewed. The lawyer had the package extended by six months, the basis of the package adjusted to include the cash value of all benefits, the sev. time (just under 24 months) credited to my DB service, and at the last moment had the value of his fee added to the settlement. Plus, an agreement as to how and when it would be paid in order to minimize my tax exposure. So for me, it was well worth engaging council.
I suspect that it very much depends upon the legislation in your geography and on past settlements. Plus the usual of age, position, etc. After that, I was entitled to 38 weeks of employment insurance.