The problems arise when a class passes from one teacher to another. On the other hand, it's probably not a bad thing that pupils should know that there's more than one way of tackling the problem. For a number of years I have taught my pupils to use the ALT key method. Some colleagues use the ALT key method too. The advantage is that pupils don't need special software when they word process at home.
Colleagues also mention the disadvantages.
It is an application-specific method, i.e. it only works in Word. The other methods, dedicating a computer to one foreign language, using keyboard overlays, specialist linguist's word processors etc., didn't have any fervent supporters. I surmised, I think correctly, that such solutions were expensive or troublesome. I'm not a fan of these, as I'm convinced that using more than one word processor drives you crazy - not my sentence, it's a quote from a help sheet I found in Newcastle University Library. As all researchers say, further research is necessary.