Optimize Transpose and append operations query

Hi han_rj, another solution:

Output

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45W8swrKC1R0lFCoFidaCjTN7GoGFUwOLW4ODM/zxDBNEIwjRFME7CG4OT8olSgoKEBkDAFEUZgFljSNzUlMQckBMTGYFGgQiTLMVwTnFhSWpRHDfeYQq01w+oYA6iD8DomLDWvlCphQ7RbYgE=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Column1 = _t, Column2 = _t, Column3 = _t, Column4 = _t, Column5 = _t]),
    RemovedBlankAndInput = Table.SelectRows(Source, each not (List.IsEmpty(List.RemoveMatchingItems(Record.FieldValues(_), {"", null})) or [Column1] = "Input")),
    // You can probably delete this step.
    ReplaceBlankWithNull = Table.TransformColumns(RemovedBlankAndInput, {}, each if _ = "" then null else _),
    AddedIndex = Table.AddIndexColumn(ReplaceBlankWithNull, "Index", 0, 1, Int64.Type),
    Ad_I = Table.AddColumn(AddedIndex, "I", each if List.Contains(List.RemoveNulls(Record.ToList(Record.RemoveFields(_, {"Index"}))), "Session", (x,y)=> Text.StartsWith(x, y)) then [Index]-1 else null, Int64.Type),
    MergedQueryItself = Table.Join(Table.RemoveColumns(Ad_I, {"I"}), "Index", Table.SelectRows(Ad_I[[I]], each [I] <> null), "I", JoinKind.LeftOuter, JoinAlgorithm.SortMerge),
    FilledDown = Table.FillDown(MergedQueryItself,{"I"}),
    GroupedRows = Table.Group(FilledDown, {"I"}, {{"T", each 
        [ a = Table.AddColumn(Table.PromoteHeaders(Table.FromRows(Table.ToColumns(Table.Skip(Table.RemoveColumns(_, {"Index", "I"}))))), "Planet", (x)=> List.RemoveNulls(Record.ToList(_{0})){0}?, type text),
          b = Table.RenameColumns(a, {Table.ColumnNames(a){0}, "Type"})
        ][b], type table}}, 0),
    CombinedT = Table.Combine(GroupedRows[T]),
    ChangedType = Table.TransformColumnTypes(CombinedT,{{"Type", type text}, {"Score", type number}, {"Medal", type number}})
in
    ChangedType