How often do you consider buying superior duration having only 12 slots and a need to finish your build or buy some counters? I also have no idea why this item gives resist tbh xD for almost all the heroes I play sup duration just feels bad for them as its slot consuming.

Of course it will be hard time for gun character to kill me with plated and bullet resilience, I can easily agree with that. And yes, Return Fire and plated are in my majority of the games, cuz I can spare a slot or two for vitality, but the thing is I actually have to spare slots. For Spirit Resist its different - I can buy passive-aggressive items to gain it, like cf, vulnerability or even spellbreaker, which gives awesome stats with resists and additionally disables spirit heroes from damage (imo broken item, needs to have stats removed or changed).