An important reason for quantitative stabilization of the solder amount is that if the solder amount varies in particular when automating, the temperature that melts the solder changes and continuous stability is lost.
In terms of quality, it also causes bridges, solder sags to the backside of PCB, and a lack of solderability.
In the conventional soldering iron system, solder is mostly sent to the soldering iron tip from a place far away with guide tube. The solder amount (length) changes due to play within the guide tube and this causes uncertain solder amount for melting and difficult for stable solder supply to the work.