Estimate time to prepare a presentation.
The conventional benchmark is roughly one hour of preparation per delivered minute for a talk that matters, which already tells you a twenty-minute conference talk is most of a working day. Slides add about twelve minutes each, and rehearsal costs about thirty percent more than the talk length per run because you stop, restart and fix wording as you go.
Content and slides
Content hours = talk minutes x preparation ratio; slide hours = slides x 0.2
Rehearsal
Rehearsal hours = runs x talk minutes x 1.3 / 60
For a high-stakes talk, yes — and specialists often quote more. A routine internal update needs far less, perhaps a quarter of that, because the content already exists.
At least three full run-throughs, with the last one uninterrupted and timed. The first run finds structural problems, the second fixes wording, the third builds fluency.