More like the appropriate heat for the job at hand. You really can't compare techniques used to solder music wire as opposed to soldering electrical components. The issue with too much heat is that you can burn off the flux which will create more issues then no flux at all. You know you are using the correct heat when the flux does not burn off and has the color of honey when your soldering is finished. Too much heat can also cause gold plating to bubble up exposing the now oxidised base metal. You will never get a good solder joint once that happens. Too little of heat means that you will have to apply heat longer and any components adjacent to your work will absorb more heat. Rule of thumb, if it takes longer then 3 seconds to flow and wet out your work then you need more heat. " Heat " is not really the correct term in most cases. Changing the size of tips does not really increase the actual temp but it does increase the conductivity which means the heat will flow faster and more evenly. Once the soldering is done always clean with alcohol and an epoxy brush. Even though some rosin core solder or flux claims to be non corrosive, that claim seems to be true in most cases before heat has been applied and not after.