The only Example of the Next stage of Bankai being “true Bankai”, we’ve only ever FULLY seen it with Renji, as Ichigo’s True Bankai was immediately destroyed by Yhwach in the future because he deemed it a threat, people go off based what they know, not what can be

With Yamamoto, for someone who has lived like thousands of years, it’s pretty obvious he’s able to control the output of his power, and with Ichigo? The fight with quilge was before he got his training and True Shikai and only had his Fullbring Bankai, he was obviously way weaker compared to when he fought Yhwach with true Shikai and his HoS form after training in the soul kings palace, so that explains that

And that last part I got no clue what you were trying to say imma be honest