There are some very key factors that will influence the answer to this question.
1. You. If you know what you are doing, or put in the research, doing it right can make a difference.
2. Space. No much point in growing £1.87 worth of radishes in a window box, other than for the satisfaction.
3. Soil. Some areas are great. Others not so much, and it can cost a LOT to turn poor soil into clay. My garden is a combo of clay and stones.
4. Location. I live in the north, and I live 650 feet above sea level. I get a growing season of about a minute.