Timer Utilities (Random Number) not working properly when number is large

When returning a random number from a large range (around 1~9000), if the timer is set to below 1 minute, the timer cannot work as intented.

For example : $tu(rnd, 1/5, 1, 9000)
The number will not return every 20 second, but instead change rapidly.
The timer will work normally when the number range is set lower, or the timer is set to above 1 minute.