> That is a very expensive expense, though. And the result might still be worse. That's entirely possible but it is hard to tell without going through the enti

> That is a very expensive expense, though. And the result might still be worse. That's entirely possible but it is hard to tell without going through the entire learning process. There might be a lot of redundancy (as we can quickly recognize mirror shapes) which if tapped at an early age might make it actually a trivial "add-on". Anecdotally you can learn within minutes to slowly parse script in reverse order. Whether you can ever get to the same speed is not clear. We do know that some cultures did use alternating script (so its clearly not impossible) but we also know that they abandoned it in the end - so there might be some disadvantages. Maybe the reason for eventually adopting uniform LR or RL instead or alternating is not the difficulty of mastering mirror versions, but being able to quickly start reading from any line on a page. For example finding the spot where you left reading, or scanning to find a relevant part. For this task the alternating form is actually less efficient as you need to jump back and forth as you go down (or up :-) the page.