This is a great question; I can't remember a time that ds was not drawing something amazing, definitely by 3 doing recognizable things. He still draws at least an hour a day, reminds me of how the great Japanese artist Hokusai used to sign some of his work: 'Man gone mad with images'. Just like there is way too much in the head and it has got to come out.
Ds definitely 'processes' things he reads and hears about via drawing; not a learning style I've ever heard of but I think it really helps him cement things.
6 or 7 seems amazingly late..?
I hope that isn't gonna jinx little dd2y9m - she is still doing big circles and yesterday she came by with two very frantic, concentrated scribbles right next to each other in sparkly purple and said - 'Mommy, these are two ballerinas! They are spinning!'
Which was a great use of what she is capable of doing, but not what most would call recognizable.
We now keep paper and pencil with us in the car, at most restaurants, waiting for stuff, etc., because if ds wants to draw something all of a sudden it's so much nicer to actually offer him that outlet than see it all bottled up.
