It depends on the spoke nipped bed thickness whether nipped washer are needed or not. Very light rims might benefit but you the rims should not need them if they are properly made. I have not used nipped washers yet. Rim cracking has so far been limited to a couple of old v1 pacenti sl23 and one carbon rim after the rider crashed badly. I really don't see the point in wasting time with them. The two failures with the pacenti rims I think we're down to spoke tension being at the limit of 1200N rather than 1150N ds rear which is were I decided the practical limit was quite quickly. Spoke tension is key to avoiding rim cracking as is spoke count being appropriate for the rider weight.
It depends on the spoke nipped bed thickness whether nipped washer are needed or not. Very light rims might benefit but you the rims should not need them if they are properly made. I have not used nipped washers yet. Rim cracking has so far been limited to a couple of old v1 pacenti sl23 and one carbon rim after the rider crashed badly. I really don't see the point in wasting time with them. The two failures with the pacenti rims I think we're down to spoke tension being at the limit of 1200N rather than 1150N ds rear which is were I decided the practical limit was quite quickly. Spoke tension is key to avoiding rim cracking as is spoke count being appropriate for the rider weight.