track time for a subroutine within a shell-script

The following code-snippet is a shell-script which does the following:

1. Track the time for a block of shell commands
2. Check if the time was less than x seconds (the example uses 10 seconds)
   
3. If the block run through too fast the script waits/sleeps a few seconds
4. Run all this within a loop so that the block of shell-commands is executed periodically

I used the script combined with a PHP script which processes a queue. The PHP script processes 1000 elements from the queue and takes about 30 seconds for that. Since just having a cronjob per minute would be not efficient enought I used this script.
The waiting-block is necessary because now and then the queue is empty ... but I think there are lot's of situations where a script like this can be usefull:

#!/bin/bash
while [ 1 -ge 0 ]; do
time_begin=`date +%s`

###BLOCK 2 TRACK - BEGIN
number=$RANDOM
let "number %= 20"
sleep $number
###BLOCK 2 TRACK - END

time_end=`date +%s`
total=$((time_end-time_begin))

if [[ $total -ge 10 ]]; then
echo "time taken was: $number : $total"
else
echo "time take was too less $number : $total"
sleep 10
fi
done