I did write about this a long time ago, but I concur with Ali Stuart about thermal mass.
I have two Weller TCP2 48 watt irons for general use, one a 3mm bit, one a 1mm bit. Anything larger and either a Weller 60 Watt and/or a Henley Solon 125 Watt come into play. They generally sort the men from the boys
Copper PCB tracks are very good heatsinks especially if they are the plated through (PTH) type with a large mass of copper on the other side.
I consider a temperature controlled 50Watt to be the best so you get good fast heat transfer. Slow heat transfer is a disaster for PCB as it will lift tracks very quickly.
In my TV servicing days (1958) at the start of PCB construction we became very wary of "lifting tracks" and soon became pretty skilled and fast at component replacement.
John