No - Sharply defined heating seasons are a lazy shorthand for "I don't care if I maximize comfort given my energy budget".
Energy Use and Comfort are strongly relatedLets look at the anonymous chart below.
Heating consumption (Gas in yellow) follows an almost square wave form
Often energy is wasted in a trade off for comfort
So without the complexity of degree days lets look at how we might (simplistically) think a need for heat might respond to a need for comfort
Better Energy Performance, Comfort or BothThe problem is either that people are heating when they should not, or not heating when they should, and the bias between the two determines whether you can have better comfort for less energy, just better comfort, or just better energy use!
But what if its comfortable ?Wasted heat is often overcome by cooling ! - If your building has a squarewave response to falling temperatures or an arbitrary heating season - you are either jeoparding comfort or performance or both.
Short post - but worth considering - As ever comments appreciated below