While many fonts now have support for both proportional and fixed width figures, some of my clients are using fonts that do not support this functionality. I use Fontself to create a numbers only version of the font that has fixed widths for all the numerals. Then in InDesign I create a grep style that automatically replaces the default figures with my newly optimised ones. Usually only do this for the table figures as this is where it is most desired. I may be infringing on copyright issues here but as it is just a fixup for specific client annual reports and I am not getting any financial benefit from it I don’t expect it to come back and bite me. Maybe I should reach out to the original designers for permission to do this for the future.