Yes and no. The first few years I planted annuals after learning about
permaculture, I mixed everything all together. The plants grew fine, but I had a really hard time thinning them (since I had to identify each one at various stages of development and decide whether I wanted a nearly-mature radish to shade an immature bean, etc. etc.) and harvesting them (since everything was scattered all over the place).
So more recently I've taken a page from Square Foot
Gardening. I don't measure out the square feet, but I plant in blocks of 2-3 square feet. When I head out to plant, I take a handful of seed packets, and I go through them in arbitrary order, plant a block from the first packet, put it away and plant a block from the next packet, etc. until I've gone through all the packets, then I shuffle and repeat, or put them away for a week or two before planting from them again in a new spot. That way the seedlings in each block are easy to identify, thin, and harvest, but (I hope) not large
enough to be vulnerable to pests.