Considering this was an ongoing series with no end in sight, this method allowed anyone at any time to jump into the next movie without worrying about catching up on anything.
The behaviors that would show up from film to film, like Bond flirting with Moneypenny, were character quirks and not things that would build over the course of the series. Part of the pleasure of Bond was that he received a new mission at the beginning of every film, which then saw him carry it out.
The first 20 James Bond films may have brought actors and filmmakers over from one film to another, but the plots of those films rarely carried over.
