While his estimate is certainly the best anyone has anywhere, it bears remembering it is only an estimate.

He missed us twice, that year: we did not stop in the Azores as we crossed the Atlantic from Fort Lauderdale to Kinsale, and we did not stop in Gibraltar when we entered the Med a full eight months later, but still before the December 31 cut-off date.

But I don't think his estimates would be much better if his survey added extra checkpoints, so I think it is just fine as it is.

Really interesting survey on cruising destinations and trends.
https://cornellsailing.com/2017/08/jimmy-cornell-where-do-all-the-boats-go/