Is SD card initialization required just once or every time the arduino resets?

Hello,
I am using SD card. It is working fine with library but my concern is something else. Due to some bug the board restarts, the code reattempts to initialize the SD card again. Is it correct to initialize it again since it has been done once. Also is there any way to know if SD card has been previously initialized or not.
Since now there is no such check implemented, the SD card is reinitialized sometimes it gives output as SD card initialization failed but normal file read/write operation is conducted successfully.
Can someone explain me the Reason for such behavior?

(deleted)

If, by reset, you really mean reset, Arduino resets, and that means restarting the SD card operation. There is nothing you can, or need to, do about this, and your problem lies somewhere else - probably in that restarting bug you don't want talk about. If your code works at all, it is probably 100% kosher, but might be time to check your power supply.