Because life with horses is never orderly.
Don't we all love the stroll to the furthest possible corner of the property? It only becomes more fun when you try to creatively weasel out of making the trek back (this is especially true if your horse is 16+ hands). Luckily for me both my guys are easily swayed by the promise of anything edible (or sometimes even just the hope of it) and will usually come galloping up handily.
Because life with horses is never orderly.
Anyone else have the joy of learning to canter on a nappy little pony beast who thinks trotting a million mph is a WAY better plan than actually cantering? Me neither actually-- I learned to canter on an ex-race horse who liked to gallop off for funsies. But, I have taught many people to canter on Woody who *insists* that the aid and the use of seat be perfect before he will canter off. It's pretty frustrating for all involved. ;)