1 stat point is equal to 4 EV, so 3 stat points won't do any good to you.
The 3 EV's WILL be wasted in any EV combination that there is.
The only reason that people invest 252 instead of 255 EV's in 1 stat is becuase theyw ant the remaining 4 EV's to get into one more stat point. This isn't much but: More the Merrier!
:)Hope I helped(:
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