There are no good guides. Most people just repeat other users' settings and also mistakes around the web. Whatever is repeated many times on the web, automatically becomes a rule. It's like with Wikipedia, where are many mistakes, but hey, it's Wikipedia so has to be true.
I'm not writing memory OC guides because on every motherboard series are slightly different values, every RAM batch can have slightly different settings, and there are always more questions than answers. One example, I recently made a set of profiles on G.Skill 6800/Hynix A, not a single profile boots on Kingston 7200/Hynix A.
Another thing is that guides like that are a lot of work, and most people just don't care to read and use them right. The last time I wrote a RAM OC guide, the competitive OC team used it against us on hwbot. They literally used my settings.
ASUS Z690-P is a budget series (no matter how it sounds) looking at the ASUS product list, and they don't care to improve BIOS or optimize it for overclocking. For that are higher ROG series and ASUS BIOS team, and in-house overclockers focus only on top mobos. Look that ASUS dropped BIOS improvements for Z690 motherboards a month after the premiere. The same for all non-Maximus series mobos.
The next thing is what was already said, the performance gain from tweaking sub-timings on Z690/Z790 is below 1%. Usually, it's a flat 0%. You can see the difference in synthetic tests but not in daily usage or games. It's still like 1-2% in synthetic tests other than the AIDA64 bandwidth benchmark where you can see something like 5GB/s more.