In ArcMap, under Scale Settings, there is an option for "Only display these scales when zooming". I would like to see this option added to ArcGIS Pro. If you have maps that are optimized for viewing at the standard ArcGIS Online / Bing Maps / Google Maps scale levels, they may not look so good at other scales. So it can be nice to use only the scales in your list when zooming with the mouse wheel or zoom in/out buttons.