I find the need to trust a stranger for the validity of blockchain data something completely opposite to what Bitcoin was created for. And if you fire up a validation rescan of the downloaded blockchain, do you then really are significantly faster. I have doubts.
Rescan doesn't revalidate blocks and rebuild UTXO. You would have to run a full scale reindex on your files but that doesn't do anything to speed up your synchronization as compared to doing the entire synchronization normally. In fact, as explained it would be even slower.
Regardless, if you were to download the entire folder and use it as a data directory, you would have to synchronize a few days of blocks. However, that defeats the purpose and opens you up to possible attacks by an adversary.