in a CJ there is a large red handled leaver between your thighs, pull that like a car hand break and it will give you a shed load of breaking for three pulls. (From memory).
It doesn't give you anti-skid breaks.
It's 10 pulls MAXIMUM,The number of pulls available will depend on the nitrogen available, the deflection of the emergency brake lever achieved during the preceding pulls. you're also right though as it is reduced to 5 pulls MAX if the gear emergency extension has been used as around half the capacity of the bottle is used to blow the gear into the down locks in that mode.
One should seek to bring the aircraft to a stop with one smooth pull and then not attempt to taxi, and correct there's no anti-skid hence the need for a smooth progressive application.
The other point is that pulling the handle and using the brake pedals at the same time will introduce nitrogen into the normal system probably rupturing it, and will render the emergency system ineffective - plenty of chance for a fiasco in the heat of the moment.