Vegetables cooked fully in advance and then reheated usually arrive soft, dull and faintly stewed. The reason is that reheating is not a neutral step; it is a second cooking that the first one has to account for.
Reheating is more cooking, not warming
Bringing a portion from refrigerator temperature to serving temperature holds the food in the range where softening continues for several minutes.
Cell walls keep breaking down throughout that period, so the vegetable ends up further along than it was when it went into the container.
Cooking to the point of perfection on day one therefore guarantees overcooking on day two, whatever the reheating method.
Carryover continues after the heat stops
Hot food holds enough internal energy to keep cooking itself for some minutes after leaving the pan, particularly in a deep mass.
A large batch cooling slowly in a container spends far longer in the cooking range than a single portion served straight away.
Stopping short and spreading the food out to cool quickly limits that, and rapid cooling matters for safety as well as texture.
Colour goes before texture does
Green vegetables lose their bright colour as heat drives out trapped air and acids released during cooking act on chlorophyll.
That change accelerates in the warm, slow phase of cooling, which is why a batch that looked vivid in the pan looks drab in the box.
Chilling immediately in cold water halts it, which is the entire purpose of blanching and refreshing rather than a chef's flourish.
Not every vegetable needs the same restraint
Dense roots and brassica stems tolerate a second heating well, since their structure survives long cooking and their flavour deepens rather than fading.
Leaves, peas, beans and anything thin lose their character almost immediately and are better cooked at the point of eating.
Sorting a week's vegetables into those that batch and those that do not is more useful than any technique applied uniformly to all of them.
Separating the finish preserves the result
Roasted vegetables can be taken most of the way and then finished in a hot oven for a few minutes, which restores the surface rather than merely warming the interior.
Blanched vegetables can be dropped briefly into a hot pan with fat and seasoning, which cooks the last stage and dresses them at once.
In both cases the prepared food is a component rather than a finished dish, which is what allows it to survive being stored at all.