You don't need a birthday to hand someone a watch. Bonnie sits well in the kind of present that turns up mid-week, for no reason beyond the fact that somebody thought of you. It reads quickly, and it doesn't ask the person wearing it to change the way they dress.
In Bonnie the choice is settled in a few minutes rather than over an afternoon. By now we know that a gift has landed when the person wears it the next day, not when it impresses them as the box opens.