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"Vast changes may be the easiest direction" - Getting too attached to an idea can bog you down. If too many users take issue with something, even if it's a big component of your design, it may be best to scrap it and try something completely different. This is related to users always being right, but just because a design idea is important to you, it isn't necessarily a good idea for you to keep.
"Given time constraints, prioritizing is key" - Certain issues users have are more important than others (hence the 4 categories the staff gave us: cosmetic, minor, major, catastrophic). When there are time constraints, dealing with every single issue can be difficult, if not intractable. When this is the case, identifying the most important issues to fix is a necessary process. There are millions of details that could be modified countless different ways, and being able to handle this situation in an organized and reasonable manner is key.
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