Yes, feasibility is a very different question to the topic of this discussion though. I don’t know if it is even possible to combine fixed Learning Steps with <1d automatic Learning Steps.
At this current stage, the <1d automatic Learning Step scheduler is not even done yet, let alone be compatible with fixed Learning Steps.
Why not just use your own if you don’t trust FSRS, or use FSRS if you do?
Well in my case for example, I would like to have my again interval be fixed at a certain amount of time whilst also keep using the automatic <1d Learning Step scheduler for the rest of the day.