A data storage system includes a non-volatile memory array controlled by a controller. In response to receipt of write data to be written to the non-volatile memory array, the controller determines whether a read count of an unfinalized candidate block of storage within the non-volatile memory array satisfies a read count threshold applicable to the block. In response to determining that the read count of the unfinalized candidate block satisfies the read count threshold, the controller finalizing programming of the candidate block and programming an alternative block with the write data.