Pick a range and go with it. Cycling calories up or down by 100-200 means nothing in the long term but trying to exactly hit some precise caloric number will quickly drive you insane.
I've decided to start calorie shifting as well to avoid plateaus. The theory behind it makes sense, and so long as when you shift upwards you don't go above your 'maintenance' calorie level, it won't do any harm.
JohnP is right, though, it doesn't need to be exact. Heck, all I plan to do is continue eating healthy, balanced foods, but kick it up to the 1800-2000 calorie range a couple days a week and not force myself to stay under 1500 cals every day.
