Short answer: use Rank when Search Console shows impressions are there, but the snippet is not doing enough work.
The CTR workflow
Spot the weak pages
Rank highlights pages with impressions and room to improve CTR, so you are not guessing which URL to edit first.
Write a better snippet
Use Rank to review proposed title and meta description changes before publishing them to your site.
Check the result
Rank stores the baseline and makes it easier to compare before-and-after performance after the change lands.
Keep the habit
This page is for people who want a simple weekly optimization loop, not a one-off audit that disappears after export.
Why CTR matters
If a page already ranks but people skip past it, there may be quick wins hidden in the title or description. Rank helps you treat those pages like opportunities instead of background noise.
If your next move is improving CTR from Search Console, Rank is built for that job.