It's fight dependent, as you mentioned. I would not bother requesting or demanding PUGs in A1 normal don't deviate further than 15y from you, that'd be selfish, so your option is pretty much to try and hit as many as you can and then Aspected Benefic anyone who wasn't hit and still needs some love. For the record, yes, 15y is an annoying range limitation and I am not sure why any healing AoE spell has 15y. Or buff, for that matter.

In a static, you will find more success if you politely ask tanks to make sure they're not too spread apart. That will ensure tanks and melee are all within reach.

Nocturnal Aspected Helios is like Succor. What you see is what you get, shield wise.