Spokeswoman Emilia Mazur said once Winning Wheel winners presented their ticket, Lotto found a weekend that suited them to appear on the draw.
Ms Mazur said the biggest Lotto non-claimant in New Zealand missed out on $3 million in 2003.
Near-misses include a Havelock North man who claimed a $250,000 prize two weeks ago - less than two months before the ticket expired. The man found the winning numbers in a drawer at home.
Last month, a Whangarei punter claimed a $166,667 prize that was due to expire this month.
And an Auckland man cashed in a seven-month-old Lotto ticket last October - to win $1 million.
Ms Mazur said thanks to media interest, big jackpot winners usually collected their prizes within a couple of days, but last year, a Christchurch ticket that won $22.6 million went unclaimed for a month.
Lotto tracked down the winner to tell him he had won.