Overrated beginner mistakes — what would you do?

Mostly thinking out loud — feel free to push back hard. Looking for honest feedback, not validation. Posting this here because the relevant subreddit has gotten too noisy lately.

Spent the last few weekends digging into this and the deeper I go the more questions I have. Posting this here because the relevant subreddit has gotten too noisy lately. Not sure if this is the right place to ask, mods please remove if it is not.