how to organize the data ?

FWIW - you can also do this with formulae if you prefer:

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Not saying you "should" just that you "could"

In principle, yes:

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however it would lead to a large precedent range (B:IV) which would not be ideal.

Should you opt to use a formula then you should calculate the COUNTA* once only and reference the result thereafter.

* if you have interspersed blanks (B1:IV1) then COUNTA would not suffice in terms of determining column requirement and you would use a LOOKUP or MATCH construct instead.

You will note that within the function detailed in my previous post COUNTA is listed twice.

It follows that in this form the double calculation will be repeated for every cell that contains the formula.

Wherever possible try to minimise repetitive calculations - specifically where the result is constant for each calculation.
Here the COUNTA result will be the same for every row that uses the function (the result never changes given the precedent range is the same for each calculation)

What we would suggest is that you calculate the COUNTA separately and all subsequent calculations then refer to that single result
(in this instance given magnitude of precedent range it might make sense to use a new sheet to hold this value)

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Then revise the formulae on Sheet1 to use this result rather than repeatedly recalculate it:

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Again, to be clear I am not saying you *should* be using formulae for this.
If your data set is large then a VBA approach is the more sensible (where viable).