Unintentionally I had lots of practice removing my mistakes this week.
I applied too bright a blue to the mountain in an effort to make it darker in parts. I applied too much green to the foreground tree area on the right. I applied too thick yellow to the top-most lake area.
Fortunately I was able to rectify most of these mistakes. With oil, it is possible to lift fresh paint off the surface without too much difficulty. This was my first experience of doing so.
After 3 mistakes and 3 corrective actions in rapid succession, I have learnt that I do not need to be so timid in applying paint in the first place. However, I still need to use some caution as the remains of my last mistake on the lake area is still clearly visible.