I find there's a sweet spot for Anki when the daily review of already-existing cards takes 20 minutes. If the daily review takes more than 25 minutes, I try not to add any cards that day.
I have mine set to 20 new cards/day and 200 remember cards/day. This seems to steady out at about 20 mins day. That said, I wish Anki had a time-boxed mode, where it measured my speeds and then just chose the right balance of new cards.
(Cards added above the new card limit go into a queue for future days automatically.)
You can kind-of achieve this by setting it up such that new cards always appear after all reviews are completed. You can use the timebox time limit to cap based on time instead of card count -- https://docs.ankiweb.net/preferences.html#scheduler
(Cards added above the new card limit go into a queue for future days automatically.)