I remember falling off of a motorcycle in Vietnam and scraping my leg. I went to the hospital, saw a doctor within five minutes, and she charged me something like $5.00. She prescribed some medicine and as walked to the pharmacy I was sure this was going to be the "big" cost. I was pleasantly surprised when the medicine was about $2.00 so frankly accident insurance is not such a terrific benefit.
However, I have heard horror stories of individuals who come and work overseas and have a heart attack or some other terrible tragedy within the first few days of arrival. This is not so surprising considering you are excited to be going, you are not eating or sleeping properly and the food is different.
Most insurance policies will not cover you before the first 30 days and if your new employer is not sympathetic you are out of luck UNLESS
you get insurance coverage from North America before you leave. I always double covered myself with insurance both from the school and coverage from my home country ( Canada). I would do the same if I were you!