Page 43 of the INF1520 study guide states
"On the first rectangular typewriter keyboard, the keys were arranged alphabetically. This allowed for typing speeds that were too much for the typewriter’s mechanics"
At the end of the study guide is a link to a video lecture by David Kieras where he debunks that myth.
In fact after a bit of research, it appears the QWERTY keyboard is very effective at maximizing speed.
I also used to relate this bit of wisdom to my customers, now I will no longer be doing that.
GO HCI