I routinely work in two currencies, and when I enter transactions in the account of the 2nd currency, GnuCash opens the "Transfer Funds/Courrency Transfer" dialogue at every single transaction I input and asks for the exchange rate into the main currency.

It would be a great time saver to have a setting allowing to specify a time interval at which GnuCash asks for this.

i.e. if this is set to 24hrs, then GnuCash would only ask once every day for the exchange rate and then keep using this until the next day.

The interval could also be once per session, once every hour, etc...