Old allium seeds

According to Real Seeds, onions, leeks, spring onions have a seed life of 3 years max. With this in mind, I've been going through all my allium seeds and pulling out all that have a sow by date of 2020/21 to sow now in my usual random way.
It is actually the right time of year to sow Chives & Garlic Chives, Winter Hardy White Lisbon Spring onions, Evergreen Bunching onions, Feast Spring onions, North Holland Blood Red Redmate onions for salad or bulb and Senshyu yellow onions - so I'll start with these. 
Since I'm hopeless at growing bulb onions from seed, I'm going to treat them all as "spring onions" and mix together all the seeds - sow a few in a seed tray and the rest will be scattered outdoors, probably in a square block so that I don't confuse them with grass.
In January, I'll do the same with the old leek seeds and a few more onions and in March I'll scatter the remainder. 
By then, I should have some idea about what has germinated and may be usable and, if very little, the leeks etc can be sown in the same square.
I'd like to grow enough alliums that I can pull one up whenever I want a bit of onion flavour - I don't need big, eyewatering onions.