Personally, when I am ready for a martini, I want my martini, and I want it immediately. Not in a Violet Beauregarde, "I want it, and I want it now" type of way, but in an, "Okay, do I have ice? I never replaced my old mixing glass. How much vermouth do I have?" way. And before you know it, suddenly I have a project.
Freezer door martinis, however? Mix it up once, and you can have four, five, six, seven, eight martinis ready and waiting for you in your freezer. Your only homework, then, is a chilled glass and garnish — which is great for those of us who never remember to make ice.