Here's a sure-fire way to save many hours a week: time segmentation. Simply allot X minutes to each task you have planned for the day. Be sure to specify a starting time and ending time, and stick to the plan. How does this save you time? Let me count the ways:

1. Parkinson's Law says the amount of work will expand to fit the amount of time allotted to it. Therefore, open-ended tasks take more time than if the very same tasks had starting and stopping times.
    
2. You avoid pacing yourself to a lower than "normal" energy output rate.
    
3. You can actually raise your energy for the duration of the allotted time, rather than working at normal energy. A person in decent physical shape can sprint full-out for three minutes (please note, the average person cannot sprint full-out for even thirty seconds, but that is a different topic). But, asking someone to sprint "for as long as you can" will result in a lowering of overall effort.
    
4. Your brain needs variety. By switching at predetermined stopping points, you get variety without sacrificing concentration.

This idea of focusing for a defined period is not some "new age crap." In fact, it is the basis for most of the martial arts, rock-climbing, competitive shooting, and advanced sports training techniques. It's been proven in venues far more demanding than the local latte shop.