It actually took me a while to catch onto that. I remember after the first time I saw Casino Royale one of my first complaints was "why does he keep throwing his phones away, only to get a new one when he needs to do something different? Why doesn't he just have one phone to do everything?" I think it took nearly a year before someone pointed out to me he isn't just throwing phones away, he's throwing anything/everything away after it's no longer any use to him.
Because of this misunderstanding it always amused me when one of the complaints I saw many have about the Jeffrey Deaver modern Bond novel was that Bond's smart phone was used way too much.
This point is also exemplified with the death of the woman he beds to get information about the plot to blow up the jet at the airport... She was married to someone who knew the plan.. He bedded her, used her for the information and then she was killed for it, a fact that M doesn't let him forget... This is akin to the girl he uses to get to Goldfinger and then ends up getting killed and painted gold for her troubles...