What math formula determines the efficiency of one method over another

So I am doing a calculation and want to determine the efficiency of one method of doing something over the other.
Ex: Method A takes X number of days to prepare, and lasts Y amount of days.
Method B takes J number of days to prepare and lasts K amount of days
Which method is more efficient per year?
Thanks!
(This is not homework, this is out of pure curiosity)

To begin with one can assume that y> x and k > j
Number, n1 of preparations required per year for method A = 365 /(y-x)
Similarly
Number, n2 of preparations required per year for method B = 365 /(k-J)
If n1 < n2 that is if (k-J) > (y-x), then method A is more efficient otherwise method B is more efficient.