Although designed for SMD, consider you might solder wires connectors or components on large ground planes too.
I think the optimal solder temperature depends on the type of solder (leaded unleaded, new or old for rework/repairs) , the thermal capacity of the tip, and the speed on which the system reacts to temperature change of the tip.
I couldn't live without an adjustable temperature. Since a few years I have been using some faster soldering stations. Though the tips are smaller and the wattage is the same, I can now solder faster and at a quite lower temperature.