ian

I sometimes practise alternate strikes to the front a rear (tsuki) x 100 on each side. (warm up though or you'll strain your neck!) - striking both to the head and sternum.

Also, try striking a target (be careful if it is a tree, the bark can be damaged very easily; although a little damage won't kill it, if you damage the bark the whole way around it could). This feels very different and requires you to get your centre behind it and make full contact with both hands at the last moment.

Try some of that and you'll understand it. As with all training be careful not to get into too many philsophical discussions about precision and this and that and formality over which is right - what works, works, what doesn't work doesn't work. None of this is magic, people just train and reflect!