Hello,
When using FSRS, the recommended retention rate is 0.90.
As shown in this chart, the workload significantly increases beyond 0.90 retention without a proportional benefit. It’s up to you whether to keep it above 0.90, but be mindful of the increased workload.
The AnKing recently released a new video on the ideal Anki and FSRS settings. I highly recommend watching it to get the most out of the algorithm:
AnKing - Ideal Anki & FSRS Settings
I hope this clarifies things for you! Let me know if you need further elaboration. 