A sweet made for twenty and the same sweet made for four hundred are not the same recipe multiplied. Several properties change with batch size, and caterers reformulate rather than scale.
Evaporation does not scale with volume
Reduction depends on surface area, but volume grows faster than surface area as a vessel gets larger, so a big batch reduces disproportionately slowly.
Doubling the milk in the same pot much more than doubles the time, and the extended cooking browns the solids further than the recipe intends.
Caterers respond by using wider vessels, splitting across multiple pans, or shifting to formulations built on milk powder that skip the reduction stage entirely.
Cooling behaves differently at scale
A large mass of hot sweet mixture holds heat for a long time, so a slab poured deep cools slowly and its sugar crystallizes coarsely.
The fix is shallower trays and more of them, which is why catering kitchens have racks of trays rather than a few large ones.
Slow cooling of dairy products also keeps them in the temperature range where microbes multiply for longer, which is why commercial operations follow published food safety cooling guidance rather than judgment.
Hand work sets the real ceiling
Shaping is the step that does not speed up. A mixture that must be rolled while warm sets a hard limit on batch size, because it cools while people are still working.
Caterers therefore favor sweets that are poured and cut over sweets that are individually shaped, since cutting scales and rolling does not.
Where a shaped sweet is required, the mixture is made in successive small batches so each is worked at the right temperature.
Formulations shift toward stability
Catered sweets sit out through an event, so recipes are adjusted toward firmer sets, lower moisture and less delicate textures than a home version would use.
That usually means more solids, slightly more fat and less added liquid, all of which trade some fresh-made quality for the ability to hold for hours.
The syrup sweets are the exception
Sweets that sit in syrup scale well, because the syrup itself protects them and they are meant to be served from a container rather than plated individually.
They also improve over several hours as absorption evens out, which makes them one of the few items genuinely better suited to catering than to home production.
This is a large part of why the same handful of sweets appears at event after event while the rest of the repertoire stays in the shop.