How much thanks is enough? A mug, a jug or a bottomless cup?
Is it like one of those "bottomless" cups of coffee offered on some menus that, at first glance, seems like an enticing and very generous notion, but then you realise after starting to consume the beverage, "one" is actually sufficient?
To give more thanks, or to drink more coffee, is actually overdoing things.
I suppose that every situation is different, and you have to judge each one individually, seeing where things takes you.