At which training category (strength aerobic tactics defending etc) I must focus training for a target striker in order to make him progress faster at heading ?
all u can do is more 4 finishing and attacking because they do a fair bit of crossing and heading in that, it wont change drastically but it will improve in time
If you look at a player, then go to Training -> Attributes then select Training Category you will see Heading is classed as Ball Control. And obviously you want a Targetman to have good Ball Control be it heading it or played to feet.