I was wondering about a concurrent idea involved: How well aireated is your soil?. Actually more important than drainage is soil aireation. What kills a plant in a flood is not the Excess Water but the lack of AIR for long time that simply drowns/suffocates the roots. Understanding about maintaining amounts of air pockets in the soil is even more important than having the soil permanently wet. Damp soils are far more productive than wet soils. Some plants have evolved in having special breathing organs for their roots: They are the "knees" of American Bald Cypresses that wouldn't survive if they handn't "knees" protruding above the bayous. When one gardens for fresh produce as we do in our farm, the soil is amended and prepared to a)improve aireation b) to improve water retention c) to provide and improve nutrient retention d) to improve physical properties of the soil such that will allow carrots to grow their possible length. e) to improve drainage by adding sand or grit f) to correct the ph liming for neutral to plus for peas/cabbages and their relatives...here our soil if left to nature reverts to 5,5/6. Finally there's companion planting, which improves the overall performance of a site because different plants have differing water/nutrient /air needs underground including the unseen mycorrhiza fungi that seem to behave better when the hosting roots are diverse. Shrubs ( ie, rosebushes) and trees are good hosts for mycorrhiza which in return help the uptake of usually difficult to find but much needed available nitrogen and phosphorus.
However the set of vegetables normally grown commercially in any farm is a minimal proportion of garden plants commonly found in temperate regions, so we here keep modifying our soil again in my gardens to meet the specific requirements for ornamentals grouping them in beds those with the similiar needs.
Retentive properties can be improved with buried materials like films, and drainage over large areas can be improved by changing the subsoil drainage patterns with underground drains made with river stones. We have to do all mentioned as well.
So as I understand it,soil management critical in agriculture or ornamental horticulture implies in artificially changing variables while keeping a sustainable/environmental awareness with a systemic approach. Thinking with all variables at the same time not linearly just one ( ie. drainage). The rest is always site specific.
