This image is a self portrait painting of artist Chuck Close, and American photorealist artist. It took him 4 months to complete in 1969.
That is impressive dedication. I think that longest I worked on a single art piece was about a month(?) But I think that I have spent 100+ hours on quite a few pieces.
The size of the piece is unbelievable. It's huge! and it looks amazing. Is the piece you worked on for a month in large format?
Not really. about 50 x 50 cm. But there were a lot small details.