Even if you want to grow enough tomatoes to feed your family for an entire season, those plants take up a lot of space.
If rhubarb is something you only use for the occasional pie or cobbler, you might be better off just buying it.
If you raise chickens or make your own dog food at home, you might want to add a few more plants for them, too.
If you plan to preserve any of your fruits and vegetables, you’ll probably want to grow more than what is suggested.
Different soil and weather conditions, even year to year, can affect the yields from your vegetable crops.