If a missile made it to CIWS range you have already failed, its a last line defence and ideally should never have to be used. Its usefulness against supersonic missiles is also debatable, a mach 3 missile travels about 1km per second which gives ciws maybe 3 seconds to engage it.
Even if you hit it say 1km out the remains of the missile is still gonna hit you at very high speed.
Chance of missiles reaching within 30km of any warship is quite high because antiship missiles skim just above the water avoiding detection and using the sea clutter as cover. There is also the earth curvature thing that results in a radar horizon.
So what does the PLAN warship do? Every ship mounts a secondary surface search radar high above on top of the mast. This appears as in a globular dome, and is referred to as the Type 364 radar. This radar is optimized for searching and scanning for sea skimming targets, reducing sea clutter. The location of the radar means it has an extended radar horizon. When a missile pops up over the radar horizon, the you can get warned earlier. The radar then queues the HQ-10 and the 730/1130 CIWS ahead in anticipation of the missile.
In the 055, the Type 364 is succeeded by four panels of X-band radar on top of the pyramid mast.
In addition, PLAN warships mount ESM on high above the mast. Usually there are two pairs situated on the side of the mast. On the 055, the ESM is mounted even higher than the X-band radar, in the form of two half cylindrical objects mounted at the very top of the pyramid right at the base of its kebob mast that holds the TACAN and communication arrays.
The need for more advanced warning from an extended radar horizon is also noticed by the USN, which is why AEGIS Baseline 9 upgrade now requires adding a small secondary radar in the form of the SPQ-9B radar on top of the mast
As for supersonic missiles, PLAN doesn't have much faith on using 20mm like USN does, they went to a 30mm that is more than half of the shell weight, has much greater hitting power and can sustain its velocity over a greater range. A 730 uses a 30mm Gatling gun similar in RPM to the GAU-8 Avenger used in the A-10 attack aircraft which is used to shred tanks. The use of 30mm is in line with the Russian preference, using AK-630 and Kashtans, and the Russians certainly know their supersonic missiles, and I trust they would know how to defend against such. We also see the Dutch going with the 30mm, with the Goalkeeper using the GAU-8 gun.
If that is not all, PLAN choose to double rate of RPM on the 730 from 5000 to 10,000, to create the 1130. So there is something going on there. But even with 30mm and doubling the rate is not enough, recently we have seen the shells these guns are using are discarding sabots. This means they are solid shells designed to kill a target completely kinetically, shredding it to pieces.
Yet with all the measures, the prime position of the CIWS is the rear due to its vulnerability and the spot is given to HQ-10, going from two Gatling guns fore and aft in the 052C to Gatling gun in front and close range missile in the rear.
Of course they and every navy in the world are not saying their studies and results in public, so we have to rely on their actions and body language.