I packed twice. Once on the Bodmin 300 in 2007 when my rear derrailuer destroyed itself in the first 50km. I converted the bike to single speed but lost too much time to make the Lands End control in time.
Other time was on the Kernow and South West 600 in 2008. I'd had all the early season off with a broken collar bone and missed the BCM etc. Before attempting the k&sw 600 I did do a 200km test ride which went ok.
Apart from a lower level of fitness than normal before this ride my daughter had been ill and waking me up every night that week at 3am. So I was short on sleep. I got to Penzance towards the back of the field but I was ok.
The night section from Penzance to the sleep stop at Bude didn't go well. I couldn't stay awake. I had a couple of catnaps in bus shelters and crashed into a hedge when falling asleep on the bike. Got to Bude but with no time in hand. Had a rest, not really a sleep for about 30 minutes then went on. The next bit of the ride is easy until after Holdsworthy and then it gets really lumpy. The buzzard must have sensed I was at the back of the pack, easy meat and had a go at me. I knew I was in trouble when a bunch of women on MTB doing a charity ride overtook me going up a hill. The route went past my house(ish) at 400km and I was out of time for the next control so I packed there and then.
I've DNSd twice, once due to weather (local 200km, lots of rain) once due to lack of lead in my pencil ( tough BCM meant a 400 round cornwall the following weekend wasn't possible )
I have done a couple of BCM where there was a high drop out rate but I finished ( 2006 and 2009 )
Finished a 200 in Devon/Cornwall when it rained all day, big rain and then blew a gale. And my lights kept failing (i'd given my spare light to a friend)
Finished a local 200 after crashing at 100k, think I was concussed large grazes and bruising
Finished a local 100 after crashing, My brakes wore out in the wet and braking with your foot doesn't work on twisty 25% gravel lanes. I ripped up my new coat on that occassion
The overall packing rate for PBP might have been in excess of 25% but for UK entrants it wasn't so I don't count that as a "ride other people packed but I didn't"
I always think it's easier to ride to the end of the event than to mess about finding a train/taxi/bus/hotel
I always carry a ton of wet/cold weather gear/spare food/a map/spare lights