One of the skills everyone who works in the electronics industry in any sort of hands-on fashion requires is soldering. Soldering is how connections between electronic components and wires, or between components and a circuit board is made. If that connection is faulty, then the circuit is interrupted and current cannot flow between the components or circuit elements. To make a good connection, sufficient heat, but not too much heat, must be applied to the joint to be soldered.
To some, it seems counter-intuitive, but to avoid overheating components during the soldering process, having enough heat to heat the joint quickly is the best solution. Metcal makes some fine solder stations that are able to heat solder joints very quickly. This means that the heat does not need to be applied to the joint for nearly as long as with a low-powered iron.
If this doesn’t make sense, consider this … heat moves along the conductors. An iron with insufficient heat will be on those conductors for a long time, and the heat will be drawn away from the joint, and into the components which are larger, and act as heat sinks. On the other hand, an iron that is able to heat the joint quickly will be able to make the solder flow more quickly. Then, the heat is removed. While the initial temperature of the joint was higher, the total thermal energy applied will actually be less than with a lower temperature, inefficient iron.
This also means that the solder tips should be in good condition. A dirty tip will be less efficient at transmitting that thermal energy directly to the solder joint.