Looks like it's working as intended: as it's set up, it will trigger the state any time between 0.4-11 seconds.
Variation is added-substracted to the interval, so if you want the timing to be, for example, between 3 and 8 seconds, interval would be set to 5.5s and variation to 2.5s (because 5.5-2.5=3 and 5.5+2.5=8).
Tell me if you need any more help or I explained something poorly, English isn't my first language.
TLDR: set interval to 5.5s and variation to 2.5s 😅