A similar question:
https://forum.readlang.com/t/what-of-words-do-you-save
I think it is better to choose which words/grammar structures you want to learn and also choose part of the unknown material as “unnecessarily advanced for me, I’m leaving it for later”.
I am myself a perfectionist who tends to want to master everything 100% before moving on. However, I try to keep in mind that most learning takes place while exposing myself to uncomfortable challenges:
- reading texts with slightly higher percentage of unknown words and actually looking them up,
- tackling math problems that require hard thinking rather than those I can solve more-or-less casually,
- sight-reading piano music that requires lots of concentration rather than first-grade pieces,
- lifting somewhat heavier weight just once rather than very light weight forty times, …
Just as there is a sweet spot for forgetting while using spaced repetition, and it’s not revising things so often that you remember 100% of the answers (the ideal forgetting index is said to be 6-14%), there seems to be a sweet spot between rigour and speed in all other areas of learning.