Oh..
I was thinking on the lines that the minute specifications of 'Duration' were moderated by GM's during spell approvals and other players during Spontaneous casting (on fair play basis) that; any form of casting directly affecting other casters (such as harm type) spells will adhere towards lower value of magnitude if the spell description fits the game.
It would be a bit out of bounds for a Harm spell to last longer than 2 hours with Duration: 3, but at the same time control or change spell can last a bit longer for around twice that amount with the same duration magnitude.
---
May be the 'Duration' can be understood to move along with 'Effect' and 'Target'?:
.Higher 'Effect' will sway the spell towards higher value of Magnitude (like five to six times the hours with Duration: 3)
.Higher 'Target' will sway the spell towards lower value of Magnitude (Lowest around an hour or two with Duration: 3)
.overall "power level" can also have a effect?
