Mapbooks need a way to control the location of elements across pages. Say you have a keymap frame that covers up text on some mapbook sheets but is perfectly located on other sheets. As it is the location of an element is locked in a single place per the template, with no way to change its location. An ArcMap only extension called MapLogic used to do this by assigning an 'anchor point' to each element, (text, data frame, whatever) and then providing several ways to setup alternate anchor points on different pages. I am aware this can be done in Python, not everyone has the time to figure it out though.
Coming from this thread as a starting point:
Re: ArcGIS Pro 3.1 - Mapbooks - Vary data frame lo... - Esri Community
