I am a bit confused by your question, but I will try to answer.

I think using an internal and extenal stem piece adds to the strength of the boat. I also believe it make stripping the ends easier, and is easier to hide/correct mistakes at the ends. I also think it looks better.

It does take some more time and effort, however. Ted Moores, who wrote Kayakcraft believes they are essential, while Nick in his book does not.

I have seen great looking boats both ways.

I hope this helps.