|Canaletto, The Bucintoro at the Molo on Ascension Day|
Nowadays most oil painters would go for a general overall impression first and refine it further and further with spots of paint.
Canaletto is rhythmic and precise, like visual music. The way he achieved this look was by painting the big background tones first. When those tones were completely dry, he would go back in with paint on a long thin brush and define the smaller forms almost like calligraphy.
Because of the drying time, I would guess that he would have had several canvases going at the same time.
Overlapping forms like figures and boats were painted from background to foreground. So those stairs going down to the water were painted all the way across and allowed to dry before the figures were added over them.
As the paint has transparentized slightly over the centuries, you can see the earlier layers through the figures.