Wooden Door - Fixing Cracked & Broken Panels - Easy, Low Cost

I was watching a guy repair a wooden boat on a beach in Thailand one day. He had some glue and a thin rope he was stuffing into the spaces between the slats. When the 25 year old wooden doors in our house started to dry out and crack. I tried caulking and such, but it did not last long and popped out.
I decided to try the boat repairman's technique and it works very well. In 6 years only one crack has had to be redone.

https://www.youtube.com/watch?v=0iCE_cvX-UY

MATERIALS:
- Natural fiber string (cotton or similar)
- wood glue
- caulking

20190112: UPDATE - It's been 6+ years and the joint is still intact, has not split and has not needed any more work.