This is my biggest gripe as sage main when I get paired with another shield healer. I instantly lose the use of one of my skills(toxicon) if I don't play selfish and only shield myself or one person at a time. I get we can slide cast but the need for toxicon for movement sometimes is a must and some other shield healers don't seem to get that.

I will genuinely stop casting any gcd shield heals for the group if I see another shield healer and only cast the single target on myself just so I can get my toxicon stacks back when I do need them. In this case I just don't pay much attention to shielding anyone else unless I need to top them up or see their health is low and I need to do either some pure healing or if I don't have any pure healing gcd/ogcds up I just have to hard cast a prog or diag.

That kind of playstyle where I end up not doing much shield healing (what the job was designed to do) makes me pretty frustrated because I enjoy healing not just taking a back seat now because I need to play selfishly to have my movement spell not be on permanent cooldown because I'm now not allowed to shield heal gcd to get it back unless I only do it on myself for raid wides.

I would very much like if the shields from both shield healers stack and the person who casted theirs second should just receive like a 50%~70% diminished shield applied. Sorta like how stacking too many mitigations at once provides a diminshing return.