The current rule is that you can get accustomed to horror when you succeed in your San rolls a number of times equal to the maximum sanity loss of the cause (e.g. 6 times in the case of Ghouls as they cost 1D6 San when you see one). But I think it is far more appropiate that you become accustomed to horror after you've failed your San roll a number of times or lost a number of sanity points, as you then have learned/accepted the true reality of our universe.

For example..... If Jake sees ghouls but makes his San roll every time, he doesn't understand/accept what he is seeing and therefore must keep on making San rolls. On the other hand, if Jake fails his San rolls when seeing ghouls (and loses a number of sanity points, say double the max for the critter... in this case 12) he has accepted the concept that horrible monsters such as these exist.

This follows more closely the rules for temporary insanity as an investigator will go insane after *succeeding* his Idea roll as he then understand what he is really witnessing.

By reversing the rule it becomes also more logical why cultists and madmen can accept our true reality much better and why Pickman could interact with ghouls. They've lost enough sanity from seeing horrible beings that they not only accepted their existence but even parlay with them.

Maybe reading mythos tomes helps in accepting our true reality and the San loss from reading a tome is subtracted from the max sanity an investigator needs to lose to become accustomed to a certain horrific cause.

For example, say that Jake has read a tome about ghouls before ever having seen them, and lost 4 San from it. Now he only needs to lose 8 San (12-4) from seeing ghouls before he gets used to them as he already has read about them and therefore has a framework they fit in.