Training I set Team Cohesion - 50% Preparation - Teamwork - no rests - High for Pre Season
One week before the start of season set preparation to 30% - rest day after - high or average intensity.
I like to have the training intensity being 2 clicks away from being "Heavy" - you can individually increase/decrease the intensity of the training by trying various settings, more resting, less resting and less intense training and so on.
If I was to set up individual training (training per role) I'd defo see that the intensity of your training is never higher than the latest notch of medium.
As soon your squad gained well cohesion of each other, set training Balanced, Tactical or Ball Control. I think those are the most worthy and increasing the most important stats which you can't increase by Age (like mental attributes) or other natural development over years.