Often we get questions such as Is moving between separate attacks of the same spell unbalanced?
The trouble I always face with these questions is "unbalanced with respect to what?". All house rules and homebrew are inherently unbalanced because they introduce changes to the game. Whether they introduce new possibilities or remove old possibilities, every change modifies the balance of the game in some way.
What's more, the ways that game balance is modified is almost always widespread, highly nuanced, and difficult to discern. There is no clear way to create a finite and exhaustive list of how it interacts with game balance. These questions are incredibly open-ended. Even a simple change can lead to near-endless discussion and debate.
Even if we did have a complete list of every interaction, there would be actually-endless debate over whether this makes the change overpowered or underpowered. There is never a clear way to weigh up something like "+1 damage" vs "+5ft of movement", making discussion almost purely opinion. Discussions can even turn into complex statements about how a change "is underpowered, except for these 2 situations where it is exploitable, but if you make this change then it's mainly overpowered, but only slightly etc".
There is no metric for "how unbalanced is acceptable", so we can't even say "we've answered this question to a satisfactory extent". This is exacerbated by the site's tendency to prefer "one true answer" over "multiple helpful answers".
We also have to contend with this site's guideline that "asking questions isn't for brainstorming or getting ideas". On other sites these kinds of questions may fly, but they seem to me to be a poor fit here.
How can we handle these questions in a way that is both helpful to askers, and maintain the site's high standard for answers?