Experienced speakers, what's your prep time factor for a talk you consider useful, solid, and well delivered?

Assume "talk time" is just the time spent on stage, and "prep time" encompasses all of drafting, writing, preparing slides, editing, and rehearsal. (Including any work you spend on the talk proposal, of course.)

"For every minute of talk time, I spend ___ minutes of prep time."

Boosts appreciated.

A: 10 or less
6.1%
B: Between 10 and 30
53.1%
C: Between 30 and 60
34.7%
D: More than 60
6.1%
Poll ended at .
@xahteiwi it depends :) How long upfront do you know about having to give the talk, is it one you have given multiple times, is it an ignite or a full talk or even a workshop.
@krisbuytaert I do mean a newly written talk and not one you've done before. As for the talk type, if it's a new talk I don't think the type makes much difference in the factor; do you see things differently?
@xahteiwi I spend about the same time prepping for an Ignite as a for a full talk.