With Libre 1 and Libre 2 you don't have to rely on a phone as you can use a Libre Reader which is what I do as I find the reader much handier as it's small and I also seldom use my phone unless away from home for any length of time.
Now, after a few years with Libre, I've got a pretty good awareness of how my food and basal and bolus insulin impacts my levels and very, very seldom need to think about a correction dose before bed, but I do often take in around 20 g of carbs to keep levels up overnight if my bedtime level isn't high enough for my liking.
It's very much a learning game as we all process food and insulin in slightly different ways. So really you just have to try different strategies, take notes, review results and react accordingly.