As long as you save the sed correctly, it germinates well. Most of mine is close to 100% and what is more, the leaves leap out of the compost, they just want to grow. Partly this is to do with freshness, other factors too.
However sometimes seeds go through a dormancy. I noticed this with coriander seed I collected in May, when sown in July it took six weeks to germinate. Sowings of the same seed in mid August came up within a week. Therefore it is programmed to wait for summer heat to finish before germinating, a great clue for its best sowing period – now!
Trying things like this is a great way to learn, i love it, seeing how nature works things out.