1zpresso k ultra grinds - ULTIMATE chart

Hello, Im using my K ultra for a year now and I still have some doubts in grind size. I've read many commentaries here and sometimes I got more confused like:

"For V60 Switch using two pours, I've been setting mine currently at 4.9"

and

"I’ve tried pour over in 6-9 clicks on the K ultra."

So people are using from 4.9 to 9.0. This is a HUGE difference!
I'm using the Hario Switch, 2 pours, the first one open and the last closed. Total time 2:30 for a 250 ml cup.

Imagine it's a medium roast bean.

Is there a "ideal range" for Switch and another one for V60 ?! Because 4.9 to 9.0 sounds odd for me!
Thank you and I wish you have a great coffee time today!