Yes the barrel of the is not flexible and where the strands leave the barrel is the main stress area where the wire is most likely to break strands. When you solder the solid nature of the wire as it leaves the terminal will localize the stress area. When the wire is not soldered the flex area is longer and if you have a quality heat shrink it gives support with some give to ease the force on just a small area. I hope this helps, your mileage may vary. Tom Evans SV Tappan Zee