First, on arrival at the airport after an overseas trip one day I accidentally took a suitcase that looked exactly like mine.
I was in a hurry and did not bother to check the baggage tag against the counterfoil they had stapled to my ticket.
Since I went through the "Green Lane" I did not have to open my luggage so I was unaware of my mistake.
I was waiting at the taxi stand when an exasperated fellow traveller accosted me and demanded what I was doing with his luggage.
After sorting out the mistake we both parted amicably.
That incident made me aware of the need to make my suitcase easily identifiable as mine.
Second, on one trip to India my luggage went astray to Madras while I was in Mumbai.
I was "clothes-less" for three days until they finally delivered my luggage to me.
That experience made me aware of packing essential stuff in my carry-on bag.
Third, my fellow photographer on an assignment to Madrid in wintry weather had packed his jacket in the check-in luggage -- which arrived only five days later.
He was forced to borrow a jacket because he did not want to buy a new one.