With the original Anki algorithm the rule of thumb is your daily review load will be 5x your rate of new cards per day. So 10 to 20 reviews per day is between 2 to 4 new cards per day. Definitely not enough for language learning, which is my use-case, but may be ok for certain other things.

> 2 to 4 new cards per day. Definitely not enough for language learning

What is your expected rate of acquisition for a new language?

40*365 ~ 14 000 new cards a year - that's a ten thousand word vocabulary with four thousand cards to spare for grammar, idioms etc?

When I learned Japanese around 15 years ago I did 10k in one year. Was a great pace. Still speak it to this day, so it worked like a charm.

I try to target 35 a day, and expect to hit that at least 80% of the time.