Mixing dough question
I've been looking over many posts in this site about mixing dough with a mixer. I have a Kitchen Aid (classic) and I trying to find out the right speed to mix the dough, for bread, pizza...etc. It seems that many said not to go over speed #2, but using a high hydration dough (65% to 75%) it is impossible to form a smooth dough ball at those speeds. I have been doing mine on really high speed, some times, all the way to #10 and have to mix it for a good amount of time until it pulls of the bowl and forms a ball. I noticed that the machine gets quite warm and I wonder if the motor will over heat by using it in this way. Now, am I doing it wrong?. I seen some post where they mixed the dough on really high speed, specially with high hydration.
The second question that I have is: I make the sponge or preferment, usually I used equal amounts of flour and water. But when I mixed it with my final dough, if I used a 70% hydration on my final dough, I have to add some flour later on because it will never pull of the bowl and form a dough ball when I mixing it. I wonder if you have to add the hydration of the sponge together with the hydration of the final dough to average the total hydration. Like I said before, if I don't mix it at the highest speed, it will never form a dough ball. Sometimes I mixed he dough for about 20 minutes or a little more. Anyway, if anybody can help me out, I'll be very grateful. Thank you in advance!