It is more efficient to work with lengths of thread less than two yards long!
Much as I dislike stopping to knot and bury a thread, it does make sense to work with lengths no more than 24 inches long. A lot of books say to use 18 inches.
What I have done, though - because I dislike stopping so much - I will cut a longer length - then leave a "tail" of about half of it - when I use up the first half - then I go the second half of the thread and finish that off.