What is the difference between had better do something and had better be doing something? For example:
It's 8 AM, so I had better leave for work if don't want to be late.
It's 8 AM, so I had better be leaving for work if don't want to be late.
Does the use of had better be leaving implies that it's not really important to me wheter I will be late or not. If I mistaken, then what do native English speakers mean by using the had better be doing structure instead of had better do one?