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Do any of you actually write cover letters? Wonder if it's worth overcoming my absolute laziness to do them. I've gotten a few interviews without them, but I'm still batting like 5/20, so I wonder if that's normal or if I should be doing cover letters.

I did cover letters but did not put in much effort. I'd keep 90-95% of it the same and modify a couple of sentences as to why I was applying to that company.