When I used to practice competitive sports I spent a lot of time doing positive visualisation. This involved (track & field sprinting) visualising the timing of my foot strike, visualising of the stride motion and power transfers, (mtbing) day dreaming about railing difficult lines on my favourite tracks including visualising the bike physics (especially in the wet). Though it's only anecdotal and there were no doubt other genetic factors at play I excelled at a rate much ahead of my peers. I have tried the same with more cerebral tasks and whilst it definitely works I find I need to spend more time immersing myself in the practice with these types of tasks.
My understanding is that "visualization" does work in the sense that it forces you to think about the subject, and it's "better than nothing" for knowledge/skill based tasks.
I find it to be mostly useless for things I don't really know though, since I find myself needing to look up details I don't remember. It can be great for knowing what you don't remember though. Kind of like trying to explain the topic to someone else.
