In matters of style like this, I find that personal taste leads to the more fluid writing and reading for each person. My personal taste is too often repeated words or phrases drags down the document, even a technical one. My solution, and the approach I was taught was the more frequently a term is used in close proximity, the less need to repeat it. I would not for instance write a sentence like "A was found to be statistically significant while B was found to have no statistically significance." I would right that more like "A was found to be statistically significant while B was found not to be significant." or maybe: "Statistically, A was found to be significant while B was found not to be significant." I personally would tend to start by using the word maybe once in a sentence and if I found it still seemed too frequent start pairing to once in a paragraph or even a section. If the term has not been used in some time, it may call for a revisit.
I would apply this as long as anytime you use significant, insignificant, not significant, of no significance or other variations to always mean statistical significance, then early in the document use the full phase to make that clear, and slowly reduce the usage. If however the document could ever mix terms, say clinical significance, then I would always be clear even if it seems redundant.