It appears to be more of a knowledge and attention to detail issue than ingredients. Walt knows the variables and understands the reactions such that he can compensate.
So could one look at it that this was Walt’s way of protecting Jesse from future elimination before he betrayed Walt? Meaning, Jesse knowing the exact formula would be “safe” if he kept it to himself? Do you think Todd will learn it now that Jesse’s captive and then wack him once Jesse gives the formula up?
Fun to ponder...