This is how I'm doing it... Started at 160 (video) with the help of automatic calibration, didn't quite work so I moved up to 180, worked better but still felt a little bit off during trickier parts. Tried 200 and played a couple of hard songs. Expert Start a Band 98%, Hail to the King 98 %, Halls of Valhalla 95%. This would not have been possible with my previous calibration, so it feels like I'm getting closer and closer of finding the sweet spot that suits my playstyle.
Remember the hitbox is very lenient on single easy notes and will usually hit despite your calibration being off. This changes during trickier songs where the notes gets closer together, which causes the hitboxes to shrink. This creates the illusion that the calibration is good at some sections, but bad at others. So it's best to test out calibration on hard songs, especially with a lot of HO/PO's. It was much easier to do calibration testings when you had practice mode and could decrease the speed, but until they fix that we'll have to do it the hard way.
Songs like My name is Jonas, Landslide, China Cat Sunflower and Hail to the King are good songs to fine tune the calibration.