All four matter but not equally. Here is the priority order I use.
Rankings are the first filter.
Go to GSC and pull all your pages sorted by average position. focus on anything sitting between position 4 and 20. These pages already proved they can rank. Google thinks they are relevant. They just need a push. Updating these articles can rank faster than anything else because the hard work is already done.
Position 1 to 3 pages get checked for freshness only. If the content is still accurate, leave it alone.
Anything below position 30 needs a decision. Is the keyword worth chasing at all? If yes, it probably needs a full rewrite, not an update.
Impressions with low CTR is the second filter.
A page getting thousands of impressions but a 1% or lower CTR has a title and meta problem, not a content problem. That is easy to solve, not a full update. Don't confuse the two.
Traffic decline is the third signal.
Pull your top 20 traffic pages from 12 months ago. Compare to today. Any page that has dropped 30% or more in traffic is worth looking at. check if competitors have published fresher versions of the same topic. check if the search intent has shifted. That tells you what kind of update it needs.
What I actually update vs rewrite
Update when the core article is solid but facts, stats, screenshots or examples are outdated. Takes an hour. you will see the difference.
Rewrite when the structure is wrong, the intent targeting is off, or a competitor has clearly outclassed the page on depth and quality.
Delete or redirect when the page targets a keyword nobody searches anymore and the traffic has been zero for six months straight. Dead pages drag crawl budget and dilute site quality.
One practical system
Run this audit once a quarter. sort by position 4 to 20 first. That list is your content update queue. Work through it before touching any new articles.
New content gets attention. Updated content gets results.