SEO has changed continuously since its beginning. The main reason for this is the constant change of search engines' algorithms. Search engines are constantly updating themselves for the benefit of the users.
To date, there are more than 200 SEO criteria. But of course, a website cannot improve itself by applying these criteria from a checklist. Each criterion can have different variations and processes within itself.
These different variations and processes also lead to completely different SEO processes. You may have heard of people who do what you refused to apply. The foundations are probably the same, but they built the roof of the building from different styles and are ranked as first for the word that they want.
You probably also heard about some projects that applied the same methods as you but failed in the end. Don't be surprised.
In fact, this situation can be compared to fishing
There are many fishermen outside. Some use bait, some set a trap, some use dynamite (don't use dynamite). Some of them use a net, some do fishing from the beach and some from the boat.
As a result of these different methods, different fish can be caught. So, it means that the different tactics can be applied to different sectors. Additional measures are also necessary for more challenging words. For instance, some fish do not come to the beach, so, the fisherman who want to capture it must use a boat.
Different studies in different sectors can give the same results too.
There's nothing weird about this. You may have heard about various different methods so far. Some of these methods can take you to the higher ranks from a long route, while others might do it in a shorter time span.
These different SEO tactics are actually more related to planning. You have to create a special way according to your industry, your competition, your product and your marketing strategy and you have to proceed with that path; otherwise it might not work for you. Failure does not mean that the tactic that you used was useless. It just did not fit your expectations.
If we have a project and need a plan for it, what we need to do first is doing an in-depth research on the sector. With an in-depth research, we can determine the competition within the sector, establish our keywords and understand how our competitors are doing the SEO.
At this phase, experience comes into play and a strategy is determined according to industry competitors, competition, keywords and goals. The way to do the articles, backlinks and promotions are determined.
If you think that you don't have enough experience; then you can start with the research and prediction. Nobody is born as a SEO expert after all. You need to experience it somehow.
So, you have reviewed your competitors. You found out at least some of their methods. At this phase, you don't need to copy them. Of course, we can have similar processes; but trying different variations and doing more quality work can always carry you forward.
Change according to time and conditions:
Another point to consider while applying your own SEO method is not being static. You need to constantly review yourself and your competitors; because they are not going to stop. This is in fact a very natural thing to expect from them. They will try different methods because either they want to get ahead of you or prevent you from getting ahead.
So, it won't be an issue to change some of your methods. Continuously moving forward in the same direction won’t be very natural for Google as well.
Doing various actions regularly, such as a serious change in design, a different campaign for the products you sell, increasing in the rank of some words which are not directly in but somehow related to your sector can work wonders for you.