I've successfully used a cake six times. Honestly, it seemed to get better after the second batch. Number seven is still in secondary, so we'll see soon about that one. I'm not sure if every type of yeast will perform like that though.
My main concern with the five day method is the amount of sediment you'll have in the bottle. If you're drinking it immediately, it won't be a problem, you'll just have cloudy cider with lots of yeast in it. It won't be sparkling clear, and it may give you a little gas, but yeast is good for you, right? The quickest batch I've done was two weeks. One week in primary and one in secondary. This is with a high flocculating yeast, so it only took a week to settle out, leaving the cider crystal clear. Obviously five days has been done before, and he liked the results. Try it, but when it's finished start a new batch and try to let it go a week in primary and at least a week in secondary. It's all about building up enough 'drinkable now' cider to give you the patience to let batches go longer for smoother, more finished product
I tend to do a couple low gravity/abv batches to get me through while the higher gravity batches age.