In some cases it can take up to several months before the cards are actually sent from the bureau. In most cases it is much less. Amateurs claim QSL cards from the bureaus, and pay a minimum handling fee and postage. However, there are amateurs, including managers, who do not know how, or where, to claim the cards. Sometimes they intentionally avoid claiming the cards, leaving them at the bureau for years.
Some bureaus destroy the cards.
Some bureaus, like ours, return the cards. Some amateurs claim the cards but do not respond to cards received through the bureau. In some other countries, organizations are subsidized, and delivery is done through clubs free of charge. Some exist only as an address for incoming QSL cards. In some cases they even regularly package QSL cards, but they defer sending until they get some funds.