The option to start at a lower wpm or just to play one character a time could be useful for us software engineers who still harbor dreams of learning morse code.

40 wpm is way too much. I just want to practice at one character at a time. Maybe even start with a reduced character set, like Duolingo only teaches you a few foreign language words at a time.

Disagree with 40wpm being way to much. You want to learn the 'sounds' of the characters, you don't want to count the individual dits and dahs.

Other posters have mentioned Farnsworth spacing, which increases the gap between characters, but keeps the speed of the individual letters.

https://lcwo.net is a good resource for learning as you start from K and work your way through the alphabet.

Years ago I tried starting out with 5 wpm and 'working up', and just barely passed the 13 wpm test to get the 'Advanced' ticket. Only thing that stopped me getting Extra was that 20 wpm code test, that was still a thing in the 80s.

I let it all lapse for about 35 years and just got back into radio in '22, and tried copying some 5 wpm from W1AW, and could copy maybe 20 or 30% of that at best. So it came as something of a surprise, playing with Morsle for a few minutes, to discover I can do as well or better at 35 wpm as I can at 5.

You really get too much time at the slow speeds to engage the frontal cortex. If you learn to think your way to each letter, that doesn't scale very far.

Hee hee. But it is Farnsworthed, the default 40 WPM is quite spaced out!