## Confirmation of Scenario Execution
After clicking on the “Start” button of your scenario, a “Confirm Scenario Execution” window appears. Here it shows how many customers will be affected by the scenario. However, this number does not always represent the number of unique customers. Let´s show the example of the situation: You set up a scenario where you send 3 emails to only one customer. The Confirmation window shows that it will be sent to 3 customers, although, in reality, it would be sent to the same customer three times.
### Usage warnings
To optimize your campaign's structure, the Scenarios check and inform you about potential usage issues. Results (and possible warnings) of these checks are shown as a warning message in the sidebar of the TEST tab or in the “Confirm scenario execution” modal window when starting a campaign.
Currently, the warning messages have a purely informational purpose and should help you identify and resolve any usage issues that might negatively influence the performance of the given scenario(s) and/or all scenarios running in parallel.
Currently implemented usage checks are for the following errors:
**(1) Jinja condition error**
Occurs when a Condition node containing jinja in some of its filter’s conditions processes more than 100K customers in one run. This can be detrimental to the performance of the whole instance’s campaign structure.
Results in a warning message: _"Too many customers processed by condition node #1 containing Jinja. Don't use Jinja in condition nodes for processing more than 100K customers in one run if the personalized filters are likely to be highly unique - i.e., almost every customer might have a different final filter."_
**(2) Set property action error**
Occurs when the sum of customers entering all the Set attribute nodes of a campaign exceeds 1 million.
Results in a warning message: _"Set attribute actions count exceeds the recommended limit. Please, try limiting the "Set attribute" node usage to a maximum of 1M updates in one run."_
**(3) Dynamic wait action error**
Occurs when a Wait node with a Dynamic time period parameter (containing jinja) is processing more than 200K customers.
Results in a warning message: _"Dynamic wait node #2 is processing too many customers in one run. If possible, consider reducing their count to less than 200K by using filtering conditions before letting them enter the wait node."_
Scenario version history
Remember that you can restore deleted versions and continue working on them. These were either accidental changes or you made them for testing purposes. Find out more about Scenarios version history [here](🔗).