Although I hold you in high esteem, I must respectfully disagree. I would never, for myself, shake a Martini nor build it with vodka - just as I would never shake a Negroni nor build it with vodka. (And yes, I have done tests too).
When to Shake, when to Stir
General rule: shake if ingredients include citrus juice, cream, or egg; stir if the ingredients are all spirits (or spirits and sugar and bitters). Shaking introduces air bubbles, which change the texture and deaden flavor. For citrus, this is a good thing as it takes the edge off the acid. Shaking emulsifies egg and cream and produces a nice froth/texture. But for a drink made only of spirits, shaking diminishes flavor and kills the beautiful clarity and "oily" texture that comes with good, high-proof spirits.
Chilling and Diluting
10 seconds of shaking versus 30 seconds of stirring is not a difference that matters to me. Good on you for chilling your glasses! If you forget (like I always seem to), you can place a handful of ice in the glass while preparing the drink then dump the ice right before you pour into the glass.
Why does Bond ask for his Martini to be shaken?
I believe Bond first orders a shaken Martini in Casino Royale. It is an odd and conspicuous request. Fleming must have known this. Bond must have known this. So why order it this way?
- The internet is full of claims that Bond prefers shaking in order to keep his wits about him. This is a basic misunderstanding. First of all, a good bartender will not over dilute the drink no matter the build. Regardless, an over-diluted drink still has the same ABV and intoxicating effect.
- My personal theory is that this peculiar order was not about the drink, but about playing poker (of course!). Bond incorrectly specs the drink to build an image as a less sophisticated player and to tilt the others. He's getting in their heads and looking for reactions/tells. This is also why he orders "The Vesper" - a strange drink he invents on the spot. Again, he's watching for the other players' reactions - while also flirting with Vesper. After that, it became a quirk of Bond's character and something both James and Ian ran with.
Does This Really Matter?
Not really. The best way to make your drinks is the way you like them.
@Poker Zombie, if we ever have the pleasure to play at the same table, I'll happily make you a shaken Martini with vodka, and I'm sure you'd be willing to stir a gin one for me. By the way, I have a good recipe for "The Vesper," which is the only vodka drink I like. Happy to make you that too...but I do stir it.