I usually have several layers in ArcMap that I need to set the page definition query for. With the page definition query being a wizard with a drop-down menu, I have to open each layer's page definition query, click the drop-down menu, and choose the correct field. When I have 20 or more layers, this can be a time consuming process.
It would be a lot easier if the page definition query was a textbox, much like the Definition Query window. This way, as long as I keep the field names consistent, I can copy and paste a line of code into each layer.