Transform using %
Transform %: select your object(s) > inside transform type in the percentage width/height you want and append % + enter. I use this in Pshop/Illust/prem etc all the time.
Thanks for your feedback! I’ll leave this suggestion open, but you can already use mathematical expressions in width and height – you’ll just need to include the original value (156 * 0.5) for 50%, for instance.