To soldering pin terminals or not?

I'm part way through the EFI wiring fundamentals course. I have a friend who built trucks for general motors. He retired from the factory and is SUPER smart. He says I should put a dab of solder on the pin terminal crimp connections when I built a harness to make 100% sure they'll never come loose. I like the idea for an even stronger mechanical connection. I've also seen this advice in various forums.

However, I'm told that electrons travel on the surface of conductors, not the inside diameter. This would mean I'm decreasing the current carrying capacity of the wire by effectively turning many strands (conductors) into one at a solder joint. I think that's the case at least for AC? But DC?

What do you guys do / recommend?

Question was answered later in course. DON'T solder! It can weaken mechanical joints.

Glad you found the answer in the course! There is a time and a place for solder, I make my own PCB's and I'm an advocate for a good solder join when its needed. But for crimp terminals, when done right, they shouldn't come loose and as far as a stronger mechanical connection, the wire itself will most likely be the failure point. Also when soldering a crimp terminal, the solder often wicks its way up the conductor and creates a stress point further up past the crimps strain relief.

In short, a good crimp will last and have no detrimental electrical effects as will a good solder. but there is a time and place for each.