I followed along with Bobby Chiu's 90 Minute Art Challenge Monkeys on youtube. These are my favorites and went longer then the 10 minute timmer. The biggest temptation for the life drawing is to press the pause button on the video to finish your subject. The parent monkey with the orange baby was about 30 minutes.
https://youtu.be/CYqiiBkRO_4

Thanks Bobbt Chiu.