Hmm, that’s probably Anki’s fuzz. I guess the right way to do things is to get the current interval and multiply that by 1.5, disregarding whatever the easeFactor is.
So, you’d want to use the previousInterval from the code snippet from my guide in the other thread and modify the goodRevObj.scheduledDays = previousInterval * 1.5 instead. Similarly, you’d do easyRevObj.scheduledDays = previousInterval * <what_multiplier_you _want_for_easy?> for again, hard and easy. I’d imagine you don’t want the 1.5 multiplier for every answer button, right?
Changing the custom scheduling code like this makes the Advanced deck settings irrelevant, as everything is now managed in the code.