I find its really not worth it. I've not had high end ddr5, my ram is also 5600, cl36. But it is very overclockable. And I can get 6800 ( with high latencies) or 6400 cl30 out of it. But I choose to run 6000 cl32 ( with a few other tweaked timings) because I can get very low voltages on the cpu side (lower than normal xmp, I can run SA at 1.15 instead of xmp default that was 1.25 I think, and vddq_tx at 1.2 instead of 1.3 default xmp or 1.4 - which is what I need for those higher clocks) and just slightly higher voltage on the ram side, (1.25 > 1.35 - need 1.5 for 6400 cl30 or 6800). In terms of performance it really doesn't make a difference when you game at 4k. Stability is more important than numbers being high for the sake of being high imo.
Perhaps there's some scenarios where it would be worthwhile, some productivity work that relies heavily on ram, or perhaps some games at low res.... But me, I'm gonna stick with 6000. I did do the 6400 cl30 for quite a while, idk a year perhaps, so the ram is more than capable of handling the voltage, at least medium term, but still, I don't see the point really anymore, outside of benchmarks, which is the only time I'll ramp them up.
Having my pc work for a long time is of a lot of importance to me which is why I don't push it. At least not anymore.... took a failure for me to think differently about things.
As for theoretically whats the highest frequency you could get, it really depends on combination of cpu + ram die ( hynix is the best, and you want single rank) + motherboard (high end two slot is the best) and of course the silicon lottery. So, hard to say. There's a lot of luck to it. You'd have to experiment to find out for yourself.
There is more often than not going to be a fair bit of stability variance in all directions when it comes to running bleeding edge technology on newer emerging hardware running it. Someone with Apex with a top tier CPU might have a piece of cake time at it, but someone one a mid tier CPU and previous generation MB of lower quality even with the same bin quality memory is probably not going to have as easy a time since more than one variable factors into the equation. It runs for me on top quality hardware piece of cake this is everyone's experience no it really isn't sorry be realistic. I think it's certainly getting more approachable to run higher binned memory even on some older hardware in cases, but don't expect it to be smooth sailing for everyone. You can sometimes deduct reasonable assumptions and roll the dice a bit, but it's not really something to just generally recommend people do so.
