Error message on Workflow rule using "$AllWorkitems"

Hello,

I'm building a Workflow rule to propagate a value to all children. To do so, I use the UpdateField with $AllWorkItems as shown here.

This works well if the workitem has a few children, but with large projects, I get the following error message:

'An error occurred while executing action '1 - Update Field' in a configuration named 'Propagate Field': Unable to perform execute on related, because number of remaining executions (1500) is less than number of related objects (1501).'

Is it a bug, or a limitation of 1500 items? If this is a limitation, how can I check that I have more than 1500 children workitems without throwing an exception, in order to display a different message depending on the situation?

Thank you in advance,

Armand BOLMONT