TODO is for when you know something specific that can be improved and want to document it, not just generally that nothing is perfect.

I occasionally get to write code that is as good as I think it can be. That doesn’t mean it’s perfect, but I don’t know how to improve it.

Something I've seen Jonathan Blow do that I like is tag things // @Speed when doing a quick to type but slow to run kind of first pass.

It seems nice to have tags for places to jump where the improvements are obvious, rather than hoping to just remember/spot them later.

I think we all occasionally write code we like, but I also write code I don't like, but only the most vague idea on how to improve.

I don't want to brag about my skills, so I won't answer that.

I similarly don't want to brag about my skills in pointing out areas of improvement in code that others might think is optimal, so I won't answer that.