I think conviction is dangerous in trading. It can interfere with what you need to do, and to accept when trade is wrong/not working ( even if a trade works just after you exit). "Strong opinion, loosely held" is perhaps what you can call as conviction in trading. Does not mean get out at first sign of trouble, just that you need to follow your tested plan and not let conviction get in your way.
So yeah if you need some whys to give you conviction, then no harm but it likely will be unknowable and so just speculative.
You don't have to follow. Simply form your ideas and test them. Take the winners - the losers and costs and slippages.
So ". If the Price touched this Support level for the 3rd time and if some other conditions are met, then it will very likely breach the Support)." is fine and a testable idea, but you will still have a decent % of of failed trades.
I have not read as much, i have not even read Magee and likely wont. My path was in moving from some blogs to traderji + misc sources, none of which worked.
But finally read Adam Grimes blog and then 1st book and a lot more and that has been enough. Right now, i am busy in my own work so have not done focused study of other authors, only made a list of people whose podcasts sounded interesting. But Grimes is highly recommended. Blog is free to read, so good way to decide. And often he does give reasons on why some idea works. Maybe I could have saved a few years if i had started reading earlier - but also, it might still take a while to turn profitable even after reading. I think its hard to follow someone exactly, you have to take the ideas and then adapt it to make it work. I dont trade like him but most of ideas are from him.