Default Skill Characteristics in Call of Cthulhu

I like the skill-based system in Call of Cthulhu, but I’ve always thought that characteristics are somewhat underutilised, so I’ve decided to add the following house rule to my game…

A player may suggest the use of a characteristic instead of a skill roll to increase their chance of success, attempting the roll at one level higher difficulty: Normal requires a Hard Success, Hard an Exceptional Success, and Exceptional a Critical. The Keeper must deem the suggested characteristic appropriate: ...