When you're painting in oil, it's possible to lay down light shapes over dark ones while the dark under-layer is still wet. But to do that, you've got to keep the under-layer thin and not too wet.
That's how I painted the white stripes on this bongo. I was lucky that at this antelope at a zoo was resting long enough for me to paint this study (about 45 minutes).
Over a tinted Venetian red priming, I lightly painted the brown body without the stripes. I used a small amount of Liquin as my medium, with white synthetic flat brush for the brushes. I then painted the stripes on top of the wet paint, and they came off the brush without disturbing the layers beneath.
Having slightly wet paint can actually improve the handling of subsequent strokes, and that's why people oil out when they're going back into a dry painting.
Previously: What is oiling out?