There is some very useful conventional advice about how the sunlight varies and it aims to help people to plan land use.
In Permaculture we aim to build on this, to make all the sectors of a space have usefulness. We can use shaded areas for mixed forest growth and storage of resources such as water. We can use semi-shaded areas for mixed plantings and protective of some plants during harsh summers. It is also a great space for people to enjoy as it lowers their risk of skin cancers and enables them to enjoy communing with nature and working outdoors.
Full sun suits conventional european short lived vegetables and a variety of plants, annual and perrenial provide protection for one another against he harsh sunlight and pests. The truth is that because the ozone is thinning, many plants are struggling on the hot summer days and having partial shade from some taller companions helps them to conserve energy.