There are some interesting ideas in this thread and, quite clearly, ideas have changed with the years.

It is a fact of learning - supported by neurological research - that our brains respond more effectively when effort shifts harder towards easier: in code terms, faster to slower.  So starting a practice session at 25 wpm and slowing to 20 is more likely to succeed than starting at ten and working upwards.

Also, brains thrive on novelty.  Repetition helps - 'practice makes perfect' after all - but dull routine kills engagement.  Six, ten-minute practices is more effective then two one-hour sessions - effectively twice as good! 

As mentioned before, surprise drives home learning, and jocularity does, too.  A good joke or an unexpected tale is worth its weight in gold - or should that be brass?

Short, sharp learning with engaged learners.  Services teaching often benefitted from engagement because if the alternative to passing the telecomms was much less desirable: there's nothing like a reason to learn.  Those learning for the Merchant Marine wanted to be Radio Officers - that was the desire and learning Morse was a step towards that personal goal.

We do this because we enjoy it!

73

Chris