Here's my honest answer to your question:
Obviously, fighting a fire this time of year isn't nearly as physically taxing as fighting one in July or August, but any large fire will still wear you out. The primary reason we call for so many additional units (2nd alarm, 3rd alarm, etc.) is for manpower and not the trucks themselves. As you could imagine, it is not safe to have firefighters exerting themselves for long periods of time without some rest and rehydration, so it is always a good idea to have enough people on hand to establish work-rest schedules.
The good thing about yesterday's large fire was that it was a defensive fire, meaning that interior operations wear not feasible or safe; therefore, most firefighting operations were conducted from outside the structure. In these scenarios firefighters do not have to wear quite as much gear or become exposed to the extreme heat that offensive (interior) operations would require. From experience, however, any lengthy fire incident, such as this one, leaves you physically and mentally exhausted and longing for a nice recliner. Unfortunately for these crews, they still had about 12-16 hours left on their shift and probably made quite a few more runs after they finished with this fire.