Can't increase interval modifier beyond 2.0

I like to review my stats and tweak my Interval Modifier a few times every year. When I tried to do this today, I found that I can’t increase the interval beyond 2. The interface is imposing a ceiling of 2 when I click the up arrow control and when I manually type a value in. Is this intentional? I already have intervals greater than 2 for several decks, but for those that are currently less than 2, the interval can’t be increased beyond 2.

I’m on Anki 2.1.49, Mac 12.1. The problem persists when I disable add-ons.

After looking through the source code, I see that this is indeed intentional. In AdvancedOptions.svelte, the interval modifier is allowed a minimum of 0.5 and a maximum of 2. Why is this? If we follow the log ratio formula suggested in the Anki documentation, we can easily get a value greater than 2. For instance, if we desire a retention rate of 0.8 and currently have a retention rate of 0.95, we get an interval modifier of log(0.8) / log(0.95) = 4.35.

The interval modifier is applied on top of the existing scheduling, so a multiplier of 2 would result in Good increasing the previous interval by 5x, and with a multiplier of 4.35 your intervals are going to grow by more than 10x each time you answer good. I’m not confident that’s going to give you the 80% retention you’re expecting, and with the large delays, it’s going to take quite a while before you’ll find out whether it was too aggressive or not.

Makes sense. Thanks for the reply.