I did my e-file training with NSI,
it lasted half a day, was asked if i felt ok after this and if i would like them to go over anything that i didn't understand and was told if i ever needed any further help with it to just go along and they would help out,
there was demonstration first then we practised on a practise hand, had to do a tip and overlay first then using the e-file practise as if we would be doing a rebalance, then and only then when we looked like we had the hang of it we had to practise on the tutor and then on each other,
no i didn't feel totally competent straight away, practised on practise hand then on myself then on a few clients that i know really well, then i was away,
i only ever use it to thin product down when rebalancing or to thin product to speed up the soaking off process,
it isn't that much quicker when using the e-file to regular filing, i use it because i have arthritis,
DONT EVER USE ON THE NATURAL NAIL
HTH