Sorcery tool described here has been updated based on user feedback.
The new version of the tool (1.1) contains both the standard durations for spells and the optional long durations. You select as per your GM’s choice using the campaing duration rules field.
The unenchanted iron version is a house rule that is now explained.
The new version can be downloaded from the same location than before in Sorcery Tool for Mythras (and friends like RQ6).