I rarely crimp mine, but do in certain situations. For heavy recoiling repeaters such as 44 magnums in my lever gun or revolver I will crimp. I have neck sized and not necked sized. I try not to resize, but if I am not satisfied with the bullet tension, I will neck size. For crimped cases, I would size to iron out the crimp for straight walled cases. If you think you have pulled the neck out of center with a bottle necked case, then resizing is in order too. But that is my opinion and others my vary.
Good Shooting and Good Luck