Shield Piling Value Increments

Like piling movement speed items and critical strike chance, piling shields on top of one champion may need to slightly fall in effeciency. My suggestion is, instead of piling flatly on top of each other, each subsequent shield decreases usage by 10%. The same could be done with subsequent heals but the values may need tweaking. (I understand this is another topic but I felt like throwing out some consistency for every aspect that could potentially follow the same mechanic)

While not an entirely huge difference (Janna's level 5 shield strength is 240 and if piled on a subsequent instance reduces it to 216) it helps spread the shields more effeciently around and doesn't entirely deny dive or poke compositions on single champion focus.

I feel like with shield comps like Lulu top, Orianna mid, Janna Support and Lee Sin jungle makes piling sheilds on carries too effecient which deny specific strategies. By decreasing subsequent shield values, it opens up more windows of opportunity for other strategies but not completely removing it's availability.

A result of this are the following situations:

1. Shields can be more evenly spread towards other teammates, preventing team damage over-all.
2. All-in engages (especially ones initiated through ultimate abilities) aren't totally denied by non-ultimate shield abilities. I can also see that there are non-ultimate abilities that enable gap-closing, but this slight change could help bring the end of the spectrum (ultimate ability gap closers that intend to deal damage in one way or another) in-line with all the gap closers.
3. This also separates the good decision makers from the great ones, depending on who needs shields at that point in time.

That's my take on it, hopefully opening up many more aspects of teamfighting and decision-making!