Many times we face feast or famine when we plant crops. With proper planning you don't have to eat broccoli for 2 weeks straight because all your plants were ready all at once. With a CSA and retail sales at the farmers markets, we need to spread out each harvested crop over a long period of time in order to maintain a variety of selection. Planting or starting plants every 10 days works to ensure a continuous supply over a period of time.
We estimate our amount of each planting by taking the number of shares x 2 weeks harvest per planting. We then add 10% for seed/plant failure and then multiply by 25%. This covers any pest damage or crop failure while still giving enough production for surplus. By replanting every 10 days we have a new crop ready to pick when the last one is finishing up. If one planting is lost to weather or bugs, the subsequent planting are usually not. Conditions and weather are always changing and you increase the odds of success.
On a smaller scale for the home gardener, you can still use this timing plan to extend your harvest of certain crops. For example: if you want to harvest 1 broccoli per week for 8 weeks, instead of planting 20 plants at the same time, start 3 plants every 10 days to spread their mature harvest over a longer period. Later plantings can be used to replace early lettuce, pac choi, or spinach in the garden saving space and re-using the area. This system works well with all but a few "day length" sensitive plants (like peas). It will help you gain a larger variety of fresh food to eat over a longer period without the waste or over supply!