Hi Neil,
Yes, you can use this function by specifying number of miliseconds in it. Use it in WF only.
There is no harm in using this function if delay is considerable. There is an alternative approach for your requirement:
1. Use a count(*) funtion on the database (May be with where clause because you have mentioned that you want to check whether more data is available for processing or not, the where clause may be added on date/time.)
2. Store the output of the Count(*) in a variable and use a conditional then. This will be definitely faster than sleep.
Please try and let me know in case of any issues.
Thanks,
Akhilesh