here's the thougot:
when maintaining a series of blades at different bevel angles (say for a bevel up plane), one could extend time between grinding by moving a blade "up" a level to a higher angle.
I realize that this may be obvious but it hit me earlier as I was reading an old article on bevel up planes. It would also give you a third angle until you honed back through the previous angle but that shouldn't be a problem right?