Does N+3-3 = N?
So, how exactly does this work if one acquires and disposes of a quantity of bikes in rapid succession? If three were acquired in three weeks, and then three discharged in a week and a half, is it now simply N-3 according to the latest streak, or does it revert to N? At which point does N stabilize to the point where subsequent N+1 or N-1 takes effect?