I completely understand on all levels. When you discover a new (better?) technique you have to fight the urge to retrofit it back into the existing build which takes up precious time, and getting that time with kids is always a challenge. Miss 3 makes things very challenging for me sometimes....
And then there's Lego themselves bringing out new elements in sets which can always have uses. I have to be careful or Bricklink becomes a rabbithole to disappear down with my wallet for a while...