Yeah, I agree, there is no right or wrong way. Both may have slighty different sounds and may work better in different situations, you are the master, you choose what you want to do & when etc.
Even watch Robert Trujillo when he slaps (more Infectious Grooves than Metallica obviously) he is a very different technique, but it sounds awesome.
If you ever watch a guy that hasn't had any lessons but either a natural or practiced hard on their own, you will see all sorts of different techniques, none of them wrong.
If it works for you & doesn't hurt, it's ok
Do or do not, there is no try
#564 5 String Club