I usually mix them up -- not really by design, but as one thing finishes up, I'll stick something different in there. It may start out somewhat uniform, but by the end of the season, it gets pretty mixes.

Here is a link that might be useful: Garden blog

I usually try to mainly group things together based on growing needs but then I tuck onions, radishes and a flower or two in where ever they fit. So it ends up looking all mixed up. I think the main thing to remember when considering placement is the height of your plants and that they are not going to shade out others. Keep tall plants on the north side of your garden and the shorter to the south so that they all get sun.

Good gardening, Mary

Just started our first SFG last weekend. It's 2'x4' table top. In it now are
Back row: XXX, Touchon carrots, French breakfast radish, Romaine lettuce
Front row: XXX, scallions (seed), CA poppies, Kentucky King bush beans. The XXXs are reserved for my grandson and granddaughter. I expect these will be flowers and strawberries.

All of it good. All of it fun.

All mixed up, but I run longer beds by design (a 2.5x10 along a fence is my smallest, then a 4x8, 4x10, 4x12, and 4x15).

I have some 3' x 5' beds and a border bed that's about 3' deep. I love to mix up herbs and flowers with my vegetables. It's good for bringing in beneficials and it just looks so nice!

The best tip I got last year was putting alyssum in the garden. I plant in blocks, but I don't do the french intensive system. By putting alyssum between the veggies, it keeps the roots shaded and keeps the weeds down. The few weeds that got through were easy to pull out. Alyssum stays short and has a great fragrance. White and mixed lavenders are my favorite choices :)