John Dallman
Hero
No, it shouldn't require lots of player intelligence. Having mechanics that allow it to be more fun for intelligent players is fine.
The best example of this which I've played is GURPS Thaumatology: Ritual Path Magic. Designing spells for this on the fly requires (a) thinking of concepts quickly (b) some table lookups and (c) some addition and multiplication to get the cost. Optimising for low cost is very important, but can be done in the concept and lookup stages.
I found that with some practice and a crib-sheet that put all the tables on one page, I could design the perfect low-powered spell for a situation in a few seconds, which made the PC's lives easier and gave the GM more margin for error in encounter design.
The best example of this which I've played is GURPS Thaumatology: Ritual Path Magic. Designing spells for this on the fly requires (a) thinking of concepts quickly (b) some table lookups and (c) some addition and multiplication to get the cost. Optimising for low cost is very important, but can be done in the concept and lookup stages.
I found that with some practice and a crib-sheet that put all the tables on one page, I could design the perfect low-powered spell for a situation in a few seconds, which made the PC's lives easier and gave the GM more margin for error in encounter design.