Planting a second or third crop on the same land within the same growing season is called successive cropping. If a crop fails don't give up, replant. If a crop produces, then begins to fade - try successive cropping. Successive cropping is a good way to maximize productivity on a given piece of land. However, in addition to successive cropping you may want to stagger your plantings.
Many vegetables provide large quantities of produce within a very narrow window of time.
For example, indeterminate tomatoes produce abundantly, then fade, and squash produces great until the squash vine borer attacks. Staggering plantings in different locations withing a garden on 7 to 28 day intervals will help improve the consistency of your vegetable supply. However, be sure to separate your staggered plantings by either space or unrelated crops in order to keep pests from spreading from one planting to the next. In addition to staggering you planting dates, you probably should consider crop rotation whenever you plant vegetables. Crop rotation refers to planting different vegetables on the same land from year to year.