Power Query - Append or Unpivot first?

[GooberTron]

I have a few separate but identical tables of data which need unpivoting and appending. Are there any practical benefits to appending the tables first, then unpivoting vs. unpivoting each table before appending?

 

[ExcelToDAX]

I would assume unpivoting each table would be more efficient. If you really wanted to tell the difference, you could capture the time of execution like this link shows.