Stacking The Beatles in Excel: An Exercise in 3D stacking

Patrick2788 

I seem to be falling behind the curve here!

My formula using the thunk array was fine, but it was tedious forming the array in the first place.  I also felt I was missing out on the new VSTACK 3D capability.  I started the refactoring by defining thunks from the stacked array

LET(
   a, SEQUENCE(12),
   stacked, VSTACK(Albums3D),
   tracksϑ, MAP(a, LAMBDA(a₁,
      LAMBDA(TAKE(DROP(stacked,31*(a₁-1)),31)))),
// and so on

Then I realised that, since I know there are 31 rows set aside for the tracks within each album, I might as well use a Lambda function with the album number as a parameter.  I therefore changed to

= LET(
   stacked, VSTACK(Albums3D),
   Hdrsλ,   LAMBDA(a₁, TAKE(DROP(stacked,31*(a₁-1)),1)),
   Tracksλ, LAMBDA(a₁, TAKE(DROP(stacked,1+31*(a₁-1)),30)),
//and then ...
   a, SEQUENCE(,12),
   expanded, REDUCE(Header, a,
      LAMBDA(rollup,a₁, 
        LET(
           hdr,       Hdrsλ(a₁),
           tracks,    Tracksλ(a₁),
           col,       XMATCH(Header,hdr),
           reordered, CHOOSECOLS(tracks, col),
           VSTACK(rollup,reordered)
        )
      )
    );
   FILTER(expanded, ISTEXT(TAKE(expanded,,1)))
)

The question then is 'Why do my formulas continue to get larger whereas everyone else's gets shorter?'