Couple of weeks ago I went on a trip to Budapest to see some mates. Booked my flights - 09/08/19 to 11/08/19 - and then forwarded the confirmation e-mail to my wife, who is Canadian, a couple of days before I was due to leave.
Her iphone tried to be 'smart' by extracting the information from this e-mail and putting the flights in her calender - except of course, that her phone/account has Canadian settings.
"Why have you booked to fly out in September and coming back in November?", she asked. Cue me nearly shitting myself, thinking I'd booked the wrong dates. But, of course, it was just her phone wrongly interpreting the date format.
So I'd say not so smart after all.