Is it normal for bank drafts to be held for a full week?

The whole issue with Bank Drafts is that they are bearer specific ready-money instruments, yet the banks (many banks) refuse to treat them as such, due to the high fraud cases with such paper printed cheques. Fraudsters will get the genuine BD made of much lower amounts and then using high-end scanners and printers, using the same credentials provide you with a BD of a higher-value.

To mitigate this fraud, Banks will put the BD into deposit, have it sent across (digitally most of the time, and sometimes physically) to the issuing bank and have it verified (i.e. endorsed) from that bank, before crediting your account.

Essentially it is a trust issue with you.