There is no reason to shorten the chain from the length required to use the 11-28. It will be too short for the 11-28, if resized for the 11-23, since 4 teeth of wrap is 1 inch. Five teeth smaller might suggest a 2 inch shorter chain.
Ther will be no change in performance, using the longer chain length.
Rather than using the big/big plus 1 inch method, try the little/little method. Shift to the little ring and smallest or next to smallest cog. The chain should be as long as possible without hanging loose. As long as the lower end of the cage moves forward and creates some tension on the chain, then it's not too long.