Bear with me here.
Besides riding my bike, I am also an amateur historian.
On long missions,  WW2 pilots, to make sure they could get from point A to point B, constantly adjusted the fuel mixture on their planes(I can assume computers do the same nowadays).

In this case 'fuel mixture' is not about actual fuel taken on while riding. It is about effort level.
Oftentimes the rider who is the most efficient  has more left in the tank for later in the race, for when you really need it, crucial splits, efforts to bridge, final sprint. 
I think you see where I am going with this.
How you utilize that fuel(effort) during the course of your ride is really important.
Sounds simple enough but it is something you need to think about and be aware of.
I have seen some serious beastie boys pounding big gears at the front early in the race for no apparent reason. 
These same guys I typically never saw in the last 20 K.
It is all about being strong at the end. Everyone is strong at the beginning.
I would say over the years I have developed a reputation for being a fairly cagey rider. I don't show my hand or fly the colors until it is time. That does not mean you sit and hide, just don't turn and burn without a reason.
This is all leading me back to the original point.
Like a pilot, as a rider you need to be constantly adjusting the fuel mixture as the ride goes along. Don't waste anything. Keep something in your hip pocket for the end. 
It does take some mental effort, especially early in a ride, when you are feeling strong. Draft well.Still conserve. Still watch the fuel mixture gauge. Keep it lean. When the time comes, push the throttle to the stops and go get it. Just be careful how many times you do that and make sure it counts for something when you do.
To be sure, I am talking about primarily racing here, although this can apply to training rides as well.
Racing is always about adjusting the fuel mixture.
Training rides, it depends on your goal for the day.
There are certain rides I go on where my plan is this-someone is either going to make me ride hard, or I AM going to ride hard. Either way, I am going hard. Here I am not looking for a result, I am looking for hard miles. A completely different mindset, but one you need to utilize when the time comes. Be smart.
Adjust the fuel mixture.
It makes a difference.
Ride on.
Coach Rick