I use MCCs. Lots of them. 122 of these are common English bi- tri- and quadrigrams and, when designing the layout, I make two entries, one shifted, one shifted.
An example will help here: I have an entry for both 'the' and 'The'.
Naturally I feel my layout needs more MCCs. My layout is designed by an evolutionary algorithm that rearranges chords to optimise the number of high value, easy to remember English bi- tri- and quadrigrams that can be created.
I'd like to rework this to include logic for multiple buttons per row chords, but unfortunately I'm already hitting the upper limit of chords that can be created: I wouldn't be able to implement the results.
My assumption is that whatever handles the chord lookup could be modified to automatically capitalise a MCC if it saw a shift + a recognised lowercase MCC. This would free up over a hundred slots.
Alternatively, it may be easier to up the limit of chords that can be supported.
More info on my layout here: https://github.com/Geoff-Lillis/twiddler-oran-layout