[Thaumatology/Magical Styles] broad optional rules by school/style

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The Extra Option and Rule of Exemption perks in Magical Styles allow characters to benefit from optional rules from Thaumatology. However, when the perks benefit "ordinary" or "tactical" casting, mages must specialize the perk per spell.

What if I want to design a styles that takes advantage of an optional rule that can be used for ordinary casting of all spells?

For example, say most mages can't trade extra energy for extra skill, but the Order of Magical Misabthropes learns how to spend extra energy for extra skill. How does that work?

To me, such situations (as well as the original perks) sound like unusual background advantages/perks. But I'm not sure how to price them. Maybe 5 points if they're balanced compared to the standard system? They're not unbalanced, just unusual. So energy for skill is in, but the flexible magic "no energy cost" option is out.