Scripts added to the script section are set as definition scripts by default. A definition script is automatically executed on game launch, which is useful for declaring variables, tables & functions.
If you go to the properties tab for the script & untick the definition checkbox then it will become an execution script, which requires you to manually execute it via the call script action part.
I recommend using a mixture of all 3 script methods. I tend to use the execute a script action part a lot, as I tend to use it for accessing or updating functions I've written inside of definition scripts or for quickly accessing/updating something in the visionaire studio data structure tables.