I love using palette knives for speed and freedom in painting. Using them makes work take on a whole new looseness, letting me concentrate on shapes and values instead of getting bogged down in detail, which I have a tendency to do.
These fish, mackerel I believe, sitting on crushed ice, were perfect candidates for going under the knife. The image wasn't perfect, which takes away the detail and forces concentration on the important elements. I seem to be bolder in colour when using the knives and the strokes with those delicious dollops of paint refuse to let me lean towards any detail work.
Small size allows satisfaction in a shorter period of time, meaning I can usually finish a piece in one session. This is on a 6 x 6 gessoed masonite panel using oils.
People comment that the technique uses a lot of paint. Well, not really, not a lot more than I would use in a painting using a brush and traditional use. Of course, a larger piece will take more paint and I did a 16 x 20 to test to see how much I would use and get good coverage. I was surprised that this technique is not as lavish in paint use as many believe. I'd say that you would use perhaps double the amount of paint that you would you use if you paint modestly with a brush.
And as I always say, supplies are made to be used, not hoarded. So be generous with your paint and let it work for you.