Hilling potatoes is mainly a coverage job: keep shallow developing tubers protected from light while leaving enough active foliage above the soil to keep the plant working. A useful first cue is established stem growth, then later passes should depend on whether the ridge has settled, washed down, or allowed tubers to approach the surface.
Zucchini is usually best harvested for eating quality before the fruit reaches its maximum possible size. For many common elongated types, a medium fruit is a useful starting target, but skin texture, seed development, cultivar, and the way you plan to use it matter more than one universal length. Once a plant starts producing heavily,
Vegetable gardening becomes easier to manage once you stop treating every crop as if it follows the same instructions. Sort each crop by season, establishment method, mature habit, and harvest pattern, then move to guidance that matches that biology. Roots, leaves, legumes, fruiting crops, and long-season vegetables can share one bed while demanding different decisions.