Question on gyroangle and torpedo 'turning' (point and shoot)

Greetings

a noob with a question here.

I have manual targeting enabled and weapons officers does NOT provide me with his assistance.

So...

Some time ago I realised the point of gyroangle: when it read 000 it is the perfect time to let the eel free. Then the torpedo launches exactly staright forward from the u-boat's hull and hits (hopefully) the target.

But now I'm confused again.

I discovered that the torpedos can align themselves towards the target. So after I have set all the needed data into the TDC, i don't even need to care about the gyroangle, correct? Even if I am in a shooting position with 90AoB, and the target has already passed the point at which my u-boat's hull is facing, I can just move the periscope over the target, fire the torpedo and it will turn towards the target! I guess this is what is called 'point and shoot'.

So since the torpedos seem to automatically turn towards the target, why bother with the gyroangle?

Or what fundamental am I missing here?

Thank you in advance!