Should I try to persuade my manager that code tidying should take priority over meeting deadlines? [duplicate]

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• How can I convince management to deal with technical debt? 17 answers

My manager has tight deadlines to meet.

The current project I am working on is currently on schedule, but I've noticed a couple of quite significant areas in the code that are really badly written. (Bits of code get called two or three times, when they only need to be called once.)

The problem is, as far as my manager is concerned, the program works. As he sees it, there's no point making lengthy changes to code that will make us miss the release date, for no tangible improvement that he can see. He keeps saying "That's not a priority. It's working fine as it is."

Should I keep trying to persuade him, or should I just do what he suggests and leave it? Why or why not? Note that how to persuade management has already been covered.