And TRR itself is not sufficient. From the paper "The idea of TRR is to refresh adjacent rows if the targeted row is accessed at a high frequency. More specific

And TRR itself is not sufficient. From the paper "The idea of TRR is to refresh adjacent rows if the targeted row is accessed at a high frequency. More specifically, TRR works with a maximum number of activations allowed during one refresh cycle, the maximum active count. Thus, if a double-sided Rowhammer attack (Section 2.2) is mounted, and two hammered rows are accessed more than the defined maximum active count, the adjacent rows (in particular the victim row of the attack) will be refreshed. As the potential victim rows are refreshed, in theory, no bit flip will occur, and the attack is mitigated. However, in practice, bit flips can be further away from the hammered rows and thus TRR may be ineffective"