Comment by Macha

The best way to put it is it really wants to type what it wants to type, and if you deviate from that it will often end up just ignoring it. Whether it's the dynamic tap zones as mentioned elsewhere, or just auto correcting backwards and changing words you've already typed. Also when you go back and change a word it will also often insert additional spaces around the changed word. Or worse still if you mistype a word like say banana then backspan to ban and retype ana, it will display banana... Until you hit space and it turns it into "ban ana".