what I call or I will be back to this line later on I always do what I call a bunch of features so I create let's say for example five features and instead of trying those features one by one I try to fill the full bunch of features at once and if improvement there is it will be not very small improvement but rather a quite important improvement and this works very very well so why does it work so well well let's imagine that you have two features a future one which is just a mean computed on some feature X grouped by