With seeds, how old is too old?

[Le Taz Hot]

7. When I was new to gardening

I heeded the "experts'" advice and threw out my seeds after the current year expired. The next year, I decided NOT to throw them out and use them for the following year. I've found that each year I get a smaller and smaller yield from the old seeds but I figure even if only 20% of them come up say, in year 5, I'm still ahead because I've already paid for them.

I know I'm supposed to do all this sealing and refrigerating but I never do and I always have good results. I know, blasphemy! but it works for me.