Does the graduating interval still work behind the scene?

I have been using FSRS for about three months now. The graduating interval cannot be set anymore, because FSRS cares about that, so they say. But I observe that it is still shown in the old “deck and card sidebar during review”, and, furthermore, it still seems to do what it used to do nonetheless. I have a deck that used to have a graduating interval of two days before FSRS, and that number is still displayed. Whenever a new card graduates, it always gets an interval of two days. In another deck, with one day, it would be one. So, For whatever reason, the old graduating intervals seem to be frozen (unchangeable) since switching to FSRS, but they are still used . What gives?

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I think it’s a coincidence that you’re seeing the same graduating interval (at times). Yes, the graduating interval is still stored in there, but it’s not used in the FSRS programming. FSRS is choosing the first interval after the learning steps based on the D, S, and R calculations on the card so far, and your parameters.

It is of course possible that your history of successfully using that graduating interval affects FSRS through the process of optimization, and FSRS is essentially agreeing that it’s the right interval. But regardless, before when you used SM-2 and now that you’re using FSRS, that interval is still subject to fuzz factor, and it will wander a bit.

But you don’t have to take my word for it – If you flip FSRS off, you can change your graduating interval to something obviously wrong (how about 100?), and then turn FSRS on again (don’t forget to save). Did anything change?

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OK, I tested that, and the wrong interval wasn’t used by FSRS afterwards. So, the long non-FSRS-Pre-history controls how FSRS works a lot.

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Yeah that seems possible to me.

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