Your estimations are incredibly generous, even for somebody using a transcription pedal. The audio for the transcription jobs on sites like MTurk is often very low quality and recorded on a device that is clearly not close to the speaker(s). They are also often for things like local government meetings where the speakers are using a lot of proper nouns that you may not be familiar with. Both of these factors result in a LOT of rewinding to listen to a word multiple times.