How often is it the case that the well-planned and highly-touted event ends in anti-climax, whereas the impromptu affair - put together on a whim - exceeds all expectations? How often that the highly-orchestrated wedding reception is never somehow as much fun as the night that all started with "just a quick drink after work"?
And so it is with this year's Vuelta a España.
July's Tour De France was supposed to be the cycling showdown of a generation: the imperious defending champion Chris Froome, with no-less-a-man than 2012 champion Bradley Wiggins as his domestique, would take on the young upstart Vicenzo Nibali, and both would be looking to silence Alberto Contador, the lurking presence of a previous, darker generation of cyclists. And beyond this triumvir of talent were a host of other possible GC contenders - Van Garderen, Péraud, Taaramae, Rolland, Pinot, Talansky, Rodríguez, Horner, Valverde, Kwiatkowski. Everywhere you looked in the field, there was interest, there were stories.
Not the icing at all, but a hundred-and-thousand or two fell off the cake when Team Sky management left Wiggins out. Then Froome and Contador - both surrounded by all kinds of high-tech-ary aimed at eking out "marginal gains" over their competitors - seemed to forget a more fundamental rule of cycling: staying on your bike is better than falling off. It was a tenet that others forgot, too. Cavendish left the Tour early, Talansky left halfway through.
Next, the rest of the field seemed to disremember that in order to beat a leader - this time in the shape of Nibali - you actually have to try and overtake him on occasion. But no-one seemed interested. And so, as much as the superb commentary team on ITV tried to talk up a "fascinating" battle for the other podium spots - much like one tries to spice-up the wedding speeches by offering a spread to other guests on their cumulative length - the race was, unmistakably, an inexorable descent from the exalted to the commonplace.
Thankfully, and against all expectations, the Vuelta a España, so often the after-thought of the Grand Tour season, now looks set to be showdown the Tour could-have-been-but-never-was. Admittedly, Nibali will not be there, so it will be hard for any winner to unequivocally declare themselves the king of kings, but the narrative he represents - of the up-and-coming talent of a new generation - can be ably told by the 24-year-old Nairo Quintana. Second in last year's Tour De France, and dominant in this year's Giro D'Italia, the Vuelta has been Quintana's long-term target. His preparation - most notably a win in the Vuelta a Burgos - has been impeccable, and so it's no surprise that he's the 2.35/4 favourite.
The Vuelta was clearly never the plan for Chris Froome this season, but almost as soon as he abandoned the Tour it was mooted as his likely comeback race. He is currently the 3.211/5 second-favourite behind Quintana. In some respects those odds are understandable: he's coming back from injury; the Vuelta is an afterthought for him; and he's on record as having said that the 2015 Tour is his next major target. In other respects, though, those odds may look huge in a few weeks' time: he's been the dominant GC-rider of the last few years; he hammered Quintana in the 2013 Tour; a fractured wrist would not have seriously inconvenienced him; and for all that he might be targeting a 2015 Tour De France, I'm sure he wouldn't mind picking up a Vuelta on route.
Contador, in contrast, seems to be viewing the Vuelta as something to do when there's not much else going on, and his video comment on Twitter that he has only just been able to ride without pain does not even make the juicy 13.012/1 odds look particularly appealing.
At the odds, Froome looks the value.
*Coverage of the 2014 Vuelta a España can be found on Eurosport and ITV4.