In the circ rules, the Holds policy by item type table controls Hold Policy, Hold pickup library match, and Return policy. Saving a value for one of these three rules requires that one also save a value for the other two.

In contrast, the Default checkout, hold and return policy interface allows one to save a value for one of these three rules and leave the others set to "Not set."

Leaving a rule as "Not set" allows Koha to move on to the next most general rule, looking for something that applies to the hold or checkin at hand. By forcing the rules in Holds policy by item type to all have saved values, we require more rules to be set and managed, rather than simply falling back to default rules whenever possible.