Peter Fisher recently discussed the idea of batching in his latest Fisher Files podcast. Tim Ferriss also writes about this topic in his book The Four Hour Workweek.
Batching means doing a bunch of similar tasks at the same time. For instance, doing your 3 loads of laundry every two weeks rather rather than a few t-shirts everyday. I find that as a grad student, even I have some administration to deal with. At the moment, most of it is work I've created for myself: tracking my sleeping schedule and daily targets, cataloging research articles I've saved, editing the photos I took last night, reorganizing my bookmarks, etc. Anytime I've delayed this stuff to the morning, I've regretted it. Personally, I find that the most efficient method is batch all these tasks and do them in the evening after I come home from work. I even try to batch mindless health tasks for the evening like showering and making my lunch for the next day. Sometime it takes a lot of discipline. I don't want to make my lunch when I'm exhausted, but if I don't do it, I regret having to do it the next morning when I'm in a hurry to get on with the real work in my day.
If you've taken a computer architecture class, you know that another way to improve efficiency besides batching is interleaving. For instance, an example of interleaving is moving your washed laundry to the dryer and putting another load of laundry into the washer. The dryer takes longer than the washer so you time the tasks to complete everything in the least time, e.g. you might do 3 loads of washing and 2 loads of drying. I don't usually need to interleave. The only examples I can think of (besides waiting for laundry to finish) are waiting for my computer to finish some CPU-intensive task, waiting for my hair to dry after a shower, or being forced to take a break from the computer to prevent neck strain.