How would we use the phrase "under one's belt" if the subject is 'us'? Would it be "under our belts" or "under our belt" because it is an idiom?
For example
With a year of successfully running this company under our belt/belts...
How would we use the phrase "under one's belt" if the subject is 'us'? Would it be "under our belts" or "under our belt" because it is an idiom?
For example
With a year of successfully running this company under our belt/belts...
Both singular and plural occur for a wide variety of organs / personal attributes that any one person might have definitely only one of, or some other number.
For example, there's the Christian New Testament Revelations 2:29 - He that hath an ear, let him hear ... As opposed to Shakespeare / Caesar / Marc Antony - Friends, Romans, countrymen, lend me your ears.
Here are links to charts showing that singular under our thumb is more common than plural under our thumbs, whereas plural on their backs is far more common than the corresponding singular. And under our belt/s sits somewhere in the middle, with both singular and plural being about equally common.
I realize not all matches in those linked charts are relevant to the context here, but I think there are enough to make the charts meaningful.
For any given "idiomatic noun in multiple possession" usage, there may or may not be a marked preference for either singular or plural. In the case of under our belt/s, there's no significant preference. But few people would particularly notice which plurality you choose, since they'll probably be familiar with both (it's not a "dialect / regional variation" thing).
According to Ngram, both are about equally common. Clicking on the Google Books search links provided by Ngram Viewer confirms that both versions are well-attested.
If logic has anything to do with it (and I know natural languages are often illogical), then "our" implies a plurality of people. The speaker/writer, and at least one other.
So "Under our nose" could make sense only if one of the two people was hideously disfigured. "Under our belt" is less problematic, since it's quite possible for only one member of the plurality to be wearing a belt.
"On their back" would have been a problem once, when "they" was definitely a plurality. But today singular "they" has made a comeback, as a natural way of avoiding gendered "him" or "her" or the hideous "him/her". So "On their back" would suggest victory over a singular entity of unspecified gender, which is quite appropriate if "they" is a singular corporation.
But where "our" is used and the reference is to a body part, it feels terribly wrong to me to use the singular, whether or not nature gives a person one or more than one of that named body part.
Of course, there's also the royal "we", and presumably royal "our" to go with it, so the above doesn't apply if the speaker is a member of a royal family, or thinks that way ....