It varies really.
With Sweepers (Pokemon designed to 'sweep' the opponent team), you would generally max out speed & attack/special attack and dump the remaining 4 (4 not 6, only multiples of 4s increase stats) on one of the other stats, often HP. This applies to Bulky attackers in a similar way, except the speed EVs on HP, or on both. Mixed attacks generally have the same setup as a dedicated sweeper, except with 4 evs on the other offensive stat, though you can mix up the EVs a little.
The main cases where you maximize the worst only really occurs on walls like Blissey, who needs to invest in it's defense to work better as a mixed wall. It's absoluetly useless on sweeping Pokemon. Generally, to simplify things just use for example, Smogon EV sets, until yo uget a good feel of it.
Lol I have no idea what I typed. xD