@Defiant Yes you do avoid splash damaging multiple shields, but smaller shields also have less HP so they often lose most or all of their HP to overspill before the large shield actually goes down. Shields of the same tier but different factions don't have such an HP difference but they also can't easily cover each other fully. And in general, overspill just makes stacking many shields rather inefficient.
Still, this is the kind of the best way to get lazy shield micro, and it's a decent last barrier of protection in case your T3 goes down but the arty shell hits a T2 shield (especially Seraphim T2).
If overspill is removed, like with the nuclear repulsor shields mod, then hiding shields behind eachother by height becomes very powerful, and takes up less space than spacing out equal size shields. Such a technique is especially potent in that mod since it has absolutely huge shields.