There is no reason to be doing this if you maintain your battery as you should, and even then, for the cost of a battery over the average lifetime, even not maintaining the battery properly it'll on average not cost that much .
As you will see on Mac forums, there are many post about battery life, in which many members run the batteries plugged in almost all the time, while others run them as advised by apple.
I have seen throughout all these different posts, regardless of how people have looked after their batteries, some maintain 95% of original capacity even after a few years, and some maintain 80% all the way down to 30% only after a couple of years.
I am one of the ones who has 95% of original capacity on my Macbook after 3 yrs running it plugged in most the time, where as I have 98% on my Macbook Pro after 2months.
Morel of the story is use your Macbook as you wish, and don't let the battery dampen your experience