Simulink Sampling time and real-world clock parameter in clock

what delay issues will you get by not setting the Simulink Sampling Time to the real world time?

the Simulink Clock is arbitrary, how ever you want to clock the design. logical choices are 1 which makes the elapsed Simulink time equal to the number of clock cycles that have gone by, or to the real world clock which will make it easier to see elapsed time in terms of real time

you can get rounding errors when using "odd" clocks for Simulink Sampling time when running ModelSim simulation with comparison to Simulink. the tool may say the results did not match when in reality they do, there is just some rounding error between the two clocks