Non tutte le ciambelle riescono col buco

Literally: Not all donuts come out with a hole

Example: “Il soufflé è crollato: non tutte le ciambelle riescono col buco.” — The soufflé collapsed; you can't win them all.

English equivalent: You can't win them all

Origin: Ciambella traces back through the Abruzzese dialect to Latin cymbula, a small boat, itself from Greek kymbē, a bowl or cup — a shape genuinely echoed in a ring-shaped pastry with a hole in the middle. The proverb itself, observing that not every plan comes out exactly as intended, any more than every batch of homemade ciambelle bakes with a clean, perfect hole in the center, appears in print in Tuscan proverb collections by the 1700s, though it almost certainly circulated in speech well before being written down. Its enduring popularity owes something to its gentle, almost consoling tone — a mild, homely way of acknowledging a partial failure rather than a harsh one.