A little something called Sweet Scent is the answer. (Honey works too) Use it when it's not raining on that route to instantly call up a horde battle. By knowing what hordes are available where, one can use this to very quickly train a Pokemon in the desired spread. For example, 10 Carbos + 3 hordes of Wingull will very nearly max out a Pokemon's Speed stat with the help of Power Anklet and Pokerus. (that's 250 Speed EV's) That isn't to say Super Training is useless, it can help get those last few points needed to finish training a stat when the usual 252/252/4 isn't the desired spread.
Besides that, Hordes were only introduced this generation, so they're not exactly old... I'd be baffled by anyone who would want to do the old somewhat pain-staking method of seeking out the Pokemon that give the desired EV's one by one, however.