I don’t think that this is a metric that can be measured simply in terms of word count or panel count or anything like that. Rather, it’s about the quality of the experience, and the sense of getting value for time and money.
So i think that each issue needs to function as a single unit of entertainment, even if it’s a portion of a larger six-issue story or something. But the yardstick for measuring that sort of thing varies. Certainly, there have been silent stories that have been outstanding, and also stories that were so word-heavy that tehy were ponderous to get through.
Also, I didn’t read the issue of INJUSTICE you’re talking about, but whether whatever the effect was worked or not, I doubt that the people involved included large panels wit the intention of milking anybody. Rather, I’m sure that they were striving for big moments and epic visuals (whether those attempts came off well or not.)