Techniques are described for determining whether a non-volatile memory device is defective due to a word line that programs too fast, leading to an uncorrectable amount of data errors when programing data to the word line. In one set of examples, a set of memory cells are programmed by a series of voltage pulses applied along a word line without locking out the set of memory cells. A verify operation is then performed to see if the number of memory cells programmed above the verify level is too large and, if so, an error status is returned. In other examples, a lower limit on the number of voltage pulses needed to complete programming is introduced, and if the programming completes in less than this number of voltage pulses, an error status returned. A lower limit on the number of voltage pulses can be on a state by state basis or for all data states to complete.