Hey Seny,
I to needed a feature like this, and we are looking into adding more loop options. Currently we cannot just loop X number of times, but we do have a work around for now.
Start off with creating a table with a field called "Number" (type = textbox), add a bunch of records numbering each one from 1 to 50. Now on your screen, in the list of actions, use an Action Result to capture the number of Items to create in your Asset table. Next use the "Loop Through Table" action, and loop through your temp table. To stop your loop, use a conditional Statement at the end of your loop(but inside) that says "If Number = (the number of items to enter) stop processing more actions.
This should get you going.