In my experience, the best UX for consistency and flow was Mac OS X circa 2008. Back then, #Apple was moving more towards #OpenSource and had gotten really good at defining Human Interface Guidelines and getting developers to follow them. Basically all the apps I used had the same UX for the core things (key commands, open/save dialogs, window management, etc). Then they got distracted by iTunes and shifted to working on devices that prioritize consuming rather than creating.
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