It depends on what material your wiring harness is made of and the purity of the material. If it is copper and aluminum, the higher the purity, the better the welding and the stronger the welding.
Then, the second point is to look at the area (volume) of the welding. If the area is too large, the power requirement of the welding machine will be high, and the cost will of course be very high.
In terms of benefits, ultrasonic welding is already worth recommending from the perspective of circuit safety due to its small internal resistance. In addition, the terminals after welding can be formed, and the welding efficiency is high, which is enough to kill hot melt in an instant. (Of course, this comparison ignores the equipment price, haha)