A sun shade is always good for light that can cause flair at certain angles.. It can improve contrast also... No amount of coating can do this 100% They act more on internal flair, with some help from flair on the front element.
The only lens I don't use one on, is my 55mm Micro Nikkor that has DEEP seated elements.. That is, the lens is 1" deep from the filter ring before the front element.
Oh and my Tele-Astranar 400mm f/5.5 that has weird filter thread... not 72, but almost 77mm.. 76mm or 75mm maybe

arggggg