Lukasfab, this discussion raises it's head quite often. It normally opens a can of worms which quickly turns into a shitstorm. For me personally I am lazy and will push best practice to it's very limit but what i have learnt over the years is to have your yeast happy and healthy if your about to give it a feast, otherwise it will be a smelly lazy turd. You will end up with a reasonable beer with one pack into 1.068 wort but it will not be as good as it could have been. When I am making a big beer I have two options, sprinkle in 2 packets or (because I am also a tight arse) brew a smaller beer first then use a cup or so of that yeast cake.
Some of the faults I have detected in some of my beers are due to my laziness with yeast, the most common being a soapy note due to the yeast stressing out which is more noticeable in less malty/hoppy beers. I have also found that when I feel i might be over pitching it is better to drop the ferment temp and that helps but I would not raise the temp if I thought I was under pitching.
There are also those that are concerned with the dead yeast cell count when using yeast cake.
What was the question again.
