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I am new to bitcoin and the first client I installed was Bitcoin-Qt (Bitcoin Core v0.9.3.0-gcea5e49-beta).
After installing and downloading the blockchain I immediately created a backup file. The other day I got my first bitcoins. Should I create a new backup file every time my wallet is updated (get more coins/spend coins) or its unnecessary (my first backup file contains all info needed for recovering all transaction history for my private key)?