I use several keyboard layouts and styles in parallel. Not a coice but I am forced. It is a bad thing having so many variants. Different number of keys, layouts (laptops, desktops), national variety. I can say that I am almost as quick in typing as I was when I was less experienced but used a single layout (full size international english 104 keys, Windows). All and every changes decrease the efficiency!
(role of Fn keys, placement of Fn switch key, shape of Enter, size and positioning of cursor keys, placement of simple symbols like slash/backslash, greater/smaller, @, #, [, ], `, etc., availability and placement of Ins/Del/Home/End, all can change just a bit with a new computer/keyboard system. All this without 'creative' regrouping or arrangement of the physical keys itself (like MS ergonomic keyboard). If we add the complication of shortcuts where keyboard plays an essential role and which changes constantly from one approach to an other inside and accross software (not improving! just changing.) we can see that the problem is too big already, no need to aggravate the situation further along questionable and marginal efficiency claims. There are other parts of personal computing that can use improvements if someone is bored.)
(role of Fn keys, placement of Fn switch key, shape of Enter, size and positioning of cursor keys, placement of simple symbols like slash/backslash, greater/smaller, @, #, [, ], `, etc., availability and placement of Ins/Del/Home/End, all can change just a bit with a new computer/keyboard system. All this without 'creative' regrouping or arrangement of the physical keys itself (like MS ergonomic keyboard). If we add the complication of shortcuts where keyboard plays an essential role and which changes constantly from one approach to an other inside and accross software (not improving! just changing.) we can see that the problem is too big already, no need to aggravate the situation further along questionable and marginal efficiency claims. There are other parts of personal computing that can use improvements if someone is bored.)