it's been a while since I used Oracle on Windows but I vaguely remember that there are two steps when shutting down the Oracle service --

1. The service stops
2. The database instance shutsdown (if that's how the service was setup with ORADIM)

So the fact that the Oracle service has stopped does not gurantee the database instance is down (and so you may be copying the datafiles that are still open). The 10 seconds delay takes care of that problem.

In Unix it's easy to chec k(by grepping for the processes like SMON) but in windows I guess the only way would be to somehow read the last line of the alert log to decipher if the database stopped.