I think that’s probably a correct assessment in respect to their approach to their work. There are two instances in my experience that confirm this statement
I remember a clip from a video I have of Fred Cuming RA painting outdoors ‘sur le motif’. The painting was quite advanced when suddenly he took a 3 inch house painters brush and covered a large middle distance section with a neutral grey. Drastic – but clearly the painting was not going well.
Even more surprising was Lars Jonsson’s complete removal of a bird from one of his paintings. In one of his books he showed a step by step demonstration of an oil painting. It showed a group of six partridges in snow. All of the birds were nearing completion when the next frame had a foreground bird covered with white paper. Sure enough in the final stage the bird had gone and he used a line of bird’s footprints to lead the eye in to the main group.
The lesson is that however much effort has been put in if things are not going well ruthless rubbing out may be the only solution.