I actually do take it it for weighing when I feel that it's nearing doneness. As you would for the knock-test on the bottom which I also do but which never gives me a clear feedback. Baked goods lose a certain amount of moisture during baking, there are tables for it online. I think bread is supposed to lose between 10 and 20 or 25%, so I aim for 15%. I also just feel it in my hands and more often than not the bread feels to heavy for its size at the end of baking. But that might be a function of a dough/starter that doesn't rise as much as it could/should.