What you need to know
Similar pages split user signals and can confuse people about which answer to trust. Not every repeated sentence is a penalty, but pages with no distinct value are difficult to maintain and may compete with each other.
How to apply it
Compare the intent and unique value of the pages, improve the strongest one, and redirect or canonicalize duplicates where appropriate. Keep separate pages when they answer genuinely different questions.
Common mistake to avoid
Do not delete useful pages only because they share a few words. Make decisions based on whether the content serves distinct needs.