Shields (at least some) should decay like Locket.
Thinker on Twitter
Suggested something to @RiotSupport and they recommended me to post here. Guess I will.
Suggested that shields should decay as I personally feel they're there to counter burst and a lot of shield durations are quite long, as healing has a counter (being grievous wounds / full hp) and this would put Karma / Ivern who are top picks right now in line, with possibly even Orianna, Lulu, and Lee Sin.
Here's the twitter thread: https://twitter.com/BIGFiku/status/856027129166708737
I'm writing this after being up for 30 hours. lol. Goodnight.