What will be your approach if your SEO method doesn’t work?
If the SEO methodology doesn’t work then do the following,
First, see whether or not it's a brand new project then re-check the keywords
Then seek for relevant keywords that may be useful
Make changes in page text, title, and outline
If still not stratified then there is also another serious problems like dangerous links, penguin/panda or alternative Google penalty
I would give it 12-months and monitor my search console.
Next I'd pick 6 different pages with similar SERP ranks and performance history. I'd make distinctly different changes to each of them. I'd monitor for an additional 3-6 months.
I'd take the tactic from the winning page and use it on the other 5 pages. I would monitor all 6 pages for another 3 months to ascertain whether that tactic works across multiple pages.
What if all the checklists are correct with the website but it still not performing?
Use the tool ahrefs, check the opponent's link, the web will follow them, it will be top
If you've done with all the needed on-page seo activity, then make quality backlinks on high DA websites. You will see your SEO will perform better and better. Try to create 6-7 high quality link with good quality content.
I don't consider following checklists optimization. It's basically just box checking.
Experiment and see what works. Make sure you're relevant and useful.
Also, building backlinks is more likely to hurt you in the long-term than make a site successful.