This is correct. See the Rule 5.1 docs for a couple examples of repeats:
https://docs.hubitat.com/index.php?title=Rule-5.1#Repeat
More to come, but the Repeat, including "While..." syntax, is documented. 
You can also see this thread for some older examples, which let you do the same thing with a slightly different syntax (but it will still work): How to get Repeated Notifications using Rule Machine
