Same here, IMHO working on updating old content & fixing internal links is more productive than always linking new pages. I generally work on pages that have impressions but are not quite in the top 10 yet.
I agree; in my opinion, the old content wins the game because it does have at least some authority and data behind it. The process of bringing pages to life through minor changes, improved intent matching, and linking can be done.
Nothing fancy imo. i have seen better success recently with page updates that uses actual queries variation in gsc followed by tightening up the internal linking for those pages. slow process but pretty much consistent so far.
I have been putting more effort into topical coverage and first hand information instead of chasing keyword's alone. It seems to work better when the whole site feels useful around a topic.
One thing worth testing is looking at queries where you rank around positions 8–20 and improving those pages specifically. Fix the intent mismatch, add missing information, and strengthen relevant internal links before chasing more backlink's.