When is the best time to switch jobs?

I recently met Ankur, a senior vice-president in a reputed MNC at Gurugram. After graduating from prestigious IIT Kharagpur in 2002, he joined XYZ, an analytics firm started by some IITians. After 6 years, XYZ was acquired by ABC. It has been 16 years and he is still working in his first company.

I also know Nikhil who graduated from a normal college, but he kept switching jobs after each 3-4 years. Today he has more than 15 years of experience. In his 6th job, he has reached till VP-level.