I am reading through a manuscript that I am co-authoring with a colleague and I noticed that he used digit separators/marks for all the numbers (i.e. 2,500 instead of 2500). Maybe it's just me but I think he started using those after he's started his post-doc in the U.S.
I have checked the author guidelines of a couple of journals that are likely submission targets in our field and they dont seem to include anything about decimal/digit separators. I also checked my previously published articles and noticed that numeric values were not edited (by press editors that is) to include digit separators.
Thus my question, is there a general rule-of-thumb regarding number formatting, especially considering digit separators?