Should I negotiate my severance?

I was offered 13 weeks of severance after 13 years as a welding apprentice, and I have a few days to sign. I have read a lot of threads here and could not find my exact situation. There is a non-disparagement clause. Did anyone negotiate and succeed?

Thanks for writing this out. I went through something close to it last year, and it got easier once I kept a simple log of every call and form.