Whyyyyyyyyyyy on earth would you waaannttt to mix them all together??
OMG!!
I think that some of the problem you are having may be with your routine, you say that you 'spray twice down the leg' for example..
I dont count the number of sprays I do, I just spray across whatever bit i'm doing until it's covered and then I repeat in the opposite direction to ensure even coverage.
What if the client is larger than most? surely 2 sprays down the leg wouldn't be enough to cover the whole area??
How much solution are you using per client on average?
How close to them are you spraying?