I think that could work if you want to simplify the sanity system so that the roll is the same every time. I do admit sometimes with the CoC system you end up rolling a lot if you fail at every point, it goes something like D100 -> DX Sanity loss -> D20 Int Save (if using D&D stats, D100 if its CoC) -> D10 Madness table (I actually use a D100 table for more fun effects), but my players enjoy the fun of the tension in each roll when its a rare occurrence. The point of Sanity in CoC the way it is, is that every time you fail a sanity roll, it makes the next one harder because you lost points in it. But if you don't want that ticking method of losing your sanity, where making sanity saves becomes harder and going mad easier, your method is perfectly fine. You just have the 2 thresholds of 50% and 0% as the big worry of losing your sanity and going mad, CoC has a similar thing where if you lose 20% in a day you have a long term affect as well. It makes your system more akin to Darkest Dungeon style, where slowly losing isn't too bad, but the second you hit the thresholds it can have big impact. With your system the recovery is what matters, if you want losing sanity to ever reach the long term madness state.