I lack something in my understanding of how the mining process works.

If a miner has to loop over a block and re-calculate it's SHA256 for only 2^32 (the amount of different nonce values possible) until it finds a SHA256 with a value lower than the target value , isn't that too fast (only 2^32 possiblities per block ?) ? I know I'm missing something here ... So what am I missing ?

Thank you.