Kind of an odd question. I know for say a special attacker you wouldn’t have 4 ATK EV, but does it matter at all whether they go onto DEF, SPD, or HP?
Its one extra stat point so I’d say yeah it matters. probably not much tho
I mean specifically are there any reasons why one would go 4 HP over 4 DEF or 4 SPD?
That extra point could allow you to survive an extra hit or get a crucial ohko or 2hko, you can do the calculations on showdown’s damage calculator to see where the point would be most beneficial
4 HP is usually used to guarantee that (in some cases) the user is able to switch in on Stealth Rocks and other entry hazards an uneven amount of times or to guarantee being able to use Substitute 4 times from full health with no recovery. If you’re intending to use the Pokemon in question for Insurgence then you’ll need to calculate how much health they would have at level 120 both with and without the 4 HP EVs factored in.
If you find that you don’t need the 4 HP EVs then it very rarely matters whether the extra 4 go into Def or SpD. However, if it is a Pokemon whose Def and SpD are literally the exact same then you can use those 4 EVs to guarantee that a Pokemon with the Download ability will always get one stat boost over the other.