People need to stop calling this severance, it's not severance. Severance is a lump sum payout or your regular checks during the severance period.
This is a supplement to unemployment. It saves them a ton of money.
If it were true severance, people could ride on that and delay filing for unemployment until it ran out. They could also get a job the next day and still draw the severance. The way they work it, they save money and your "severance" ends when your unemployment runs out; they run concurrently. Think of your severance package as an add-on to your unemployment, that ends the moment the latter does, if not before if you've only been with the company a short time.
For instance, if you've been with the company for three years, you get 4 weeks plus 1.5 weeks per years of service - that's 8.5 weeks. They will stop supplementing your unemployment at that time.
If you've been with the company for 30 years, that's 4 weeks plus 1.5 per years of service, which SHOULD be 49 weeks of supplemental, but as soon as your EDD runs out, so does your supplemental. Which is why the max is 26 weeks.