Another 0 and 5 practitioner here, following Les's method in my own thumb-fingered way! As Les says, the G0 exposure places the palest detailed highlight tone where you want it, the G5 exposure places the deepest detailed shadow tone where you want it. These may be just off paper-base and DMAX, or you may choose to place them elsewhere.
I used to guestimate a grade, do a test strip for time and then fumble towards the correct settings by trial and error. Sometimes it would come quickly and other times it prove prove annoyingly elusive.
Now, two test strips and that's my base exposure pretty much in the bag with just dodging and burning to worry about ("just" he says; Hah! :rolleyes: ).
At first glance it seems like a slower and more complex way of working, but I have to say that the reverse usually proves to be the case.
All the best with your endeavours!