I think your theory is correct. Back when messages where not checksummed, the French Navy used to do exactly this and sent abbreviations three times in a row.

I think your theory is correct. Back when messages where not checksummed, the French Navy used to do exactly this and sent abbreviations three times in a row. I'm quite certain that the French Navy was not the only one to do this since our communications techniques were heavily influenced by foreign nations like the US.