Blog commenting? Need help.

I am very good at blog commenting and more than 95% of my comments get approved.
I have a website about "improving eyesight"
Where should I comment?

I made comments on posts about eyesight and natural vision care. (Not niche websites)
For eg A blog for software engineers had a post on "reducing eye strain", if I comment on that is it fine?
Is it fine as long as I comment on the posts around my niche or should I comment only on niche websites?

Also I made 6-7 comments on totally different niches (I didn't spam, I made very genuine comments) . Will I be penalised for making comments on totally different niches?

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