I use the electronics crimping tool, It's like a plier that cuts and then has the jaws for crimping on end pieces such as loops etc. You can find them cheap usually come with a few end pieces. Never had a failure. FWIW
I've noticed that also. But more important I have found that my Customers have also. This helps us peeps who are doing it right, in one way and hurts us all in another. I feel doing it the right way pays off in the long run.
Actually noses vary also, one can "get used to" some fragrances faster then others. So I agree it's almost impossible to answer, with so many variables.