I would normally agree about not tweaking without a meter, but if you have a known reference, like a laptop screen that is calibrated or a cell phone (some are fairly accurate), you can compare a grayscale ramp on there to the TV.
I have an i1d3 meter, but it's not profiled for OLED. Even so, it seems that it's close enough. I can compare what I see with my eyes to what the meter says, and I think it's in the ballpark.
No, I just used the 2-pt low to cut green. I don't have the patience to run through a 20-pt cal, and don't think all the extra time spent would be worth the minimal improvement. It's a little annoying the the red and blue low affect black level, so I can't touch those, but I don't think they're that far off, anyway.
Here's a before and after: