For comparison my radio-controlled airplane had servos ($20-30 type) which ran on 50 frames per second from a radio transmitter(command pulses or bunch of command pulses). That speed seems sufficient for R/C pilots. It's fast enough to respond for human purposes yet slow enough to be reliable in unknown environments (example, adjacent radio channels in use).
For 50 Hz frame rate the time between frames is 20 mSec.
5 & 0 has two digits similar to your figure of 500k.
Your servo drive could be more sophisticated particularly if you need for it to respond quickly (to machine sensors or machine commands or fast moving equipment). Or maybe you operate not by radio but via direct electrical hookup. Or paid more money for a deluxe model?