ARRAYFORMULA should be used only once in each formula or should it be used multiple times once for e-CodePudding

Sum the VLOOKUP results:

=ARRAYFORMULA(SUM(IFERROR(VLOOKUP(A1:A,B1:C,2,FALSE))))

Sum two cells:

=(Z1 Z2)

Sum two specific values from VLOOKUP:

=ARRAYFORMULA(SUM(IFERROR(VLOOKUP(G1:G2,H1:I,2,FALSE))))

Now I need to come up with an average of the three results:

=ARRAYFORMULA(
    SUM(IFERROR(VLOOKUP(A1:A,B1:C,2,FALSE))) 
    (Z1 Z2) 
    SUM(IFERROR(VLOOKUP(G1:G2,H1:I,2,FALSE)))
)/3

But the faithful form would be:

=(
    ARRAYFORMULA(SUM(IFERROR(VLOOKUP(A1:A,B1:C,2,FALSE)))) 
    (Z1 Z2) 
    ARRAYFORMULA(SUM(IFERROR(VLOOKUP(G1:G2,H1:I,2,FALSE))))
)/3

Both will reach the same result, my question is, what is the most correct and safe way from the standards of those who work professionally with Google Sheet?

1 → Use only one ARRAYFORMULA call for the all the formula.

2 → Use multiple ARRAYFORMULA calls, one for each specific need.

Question reason:

I still haven't found risks of using a single ARRAYFORMULA in the beginning and doing everything else within it like =ARRAYFORMULA((...) (...)) rather than =ARRAYFORMULA(...) ARRAYFORMULA(...), but I not finding risks doesn't mean they don't exist.

CodePudding user response：

One instance of ArrayFormula on the outside is both sufficient and the professional standard.

However, I must say that I don't understand your formula usage or intention from your posted example. You've got between each element, which is redundant to SUM. And like ArrayFormula, you only need one outer SUM to sum all elements in your usage.