I think the answers on these vary per country and person etc.
UserU has very different results then me getting 1-2 and even 9 texts on 1 day, I have had it installed for about a month now and have gotten 5 texts ($0.10 :p)
Hey,
Is the app running at all times? If it is, you'll see the notification icon. But sometimes the phone tends to kill it so you might not even notice the app has stopped running.
I did notice it kills it itself so that's usually when I sleep then I turn it back on when I wake up so it runs about 18 hours a day I'd say.