The deadlines are worked out by hand and checked twice because nobody trusts them

Every contract has its own dates, somebody works them out by hand, they live in a personal calendar, and they get checked twice because nobody quite trusts the arithmetic. It holds, mostly, until the person is on leave, or the contract is amended, or the one wrong entry nobody re-checked comes due.

Deriving dates from contract terms is exactly the work systems do without tiring, and hand-kept dates fail in the two most expensive ways: silently, because a wrong entry looks like a right one; and personally, because the calendar leaves with its owner. Set up once, the dates are derived from each contract, surfaced where the team already works, and owned by the job rather than a memory.