Thanks, @JMichaelTX - that's really helpful.
My understanding of the options and most profitable courses of action is much more sophisticated than it was a few days ago!
I suspect that what I'll do is assign apps to tasks incrementally (e.g. as you suggest for expansions); and to explore Ukelele for a single mapping to avoid what Tom so aptly and effectively calls 'stupid fix hotkey triggers' (that really says such a lot!) - rather than trying to work it all out in one go.
Hey, don’t take it out of context 
This was meant in relation with LaunchBar (which provides dynamical and intelligent abbrevs, in contrary to “stupid fix hotkeys” as provided by other apps. I know, KM since 8.0 also provides some intelligence, but this is in no way comparable with LB.).
This was my intended context:
But don’t forget LaunchBar. LB can take over text expansion (up to a certain degree) and it can launch your KM macros in a convenient way (i.e. without stupid fix hotkey triggers). And you can also build LB actions, similar to KM macros. Which, once you are familiar with AppleScript or JXA, is more convenient than tacking together the actions in the KM Gui.
Things you map in your keyboard layout file will be stupid and just fix :
If you map ✘ to ⇧⌥A, it will be there, “stupidly” 
I was only referring to dynamic abbreviation triggers vs fix “stupid” hotkey triggers.
Tom,
OK 
!
Well - a week ago I think I would have twisted myself inside-out just to get any absurd combination of keys like SHIFT-CTRL-OPTION-CMND-fn-r-p-l to trigger a reply somewhere, somehow.
That's what I call an unwise fix, which I might be tempted to use to Trigger something in KM!
Now I can see much better ways to do that.
Ok, slowly but steadily I’m getting your problem 
I apologize if I already mentioned this, but I have evolved to using "Trigger by Name", or actually MACRO: Execute Macro by Name (Spotlight) by @DanThomas for most of my macros, especially those that I don't use many times a day.
If I can't find an intuitive, mnemonic (for me) hot key, then assigning some esoteric hot key that I will never remember is a waste of time.
Yep. Me too. I tried the intelligence of KM, but it is not that great. (Well, better than in KM7.)
In addition it has an UI problem: If you rethink, you have to press several times Delete until you can enter your new search abbreviation. (Otherwise your search string will just be appended to your existing one.) — Similar as in macOS’ Spotlight, pretty debil.
So, still, my preferred way (since I can’t remember overly complex combos) is LaunchBar, also for launching KM macros. (see there). And for snippets anyway.
Nothing easier than that.
Exactly!
I've started a table (simple) in Numbers. I do expect to have some obscure ones: letters that will never appear together because always preceded by a comma (which almost always requires a space after it) can aid simplification. Like ,the for 'Thank you for helping me', which would otherwise have to be tyfhm, makes life easier.
I've got a ridiculous number of hotkeys set up, mostly in KM but also some in Butler, the Keyboard system prefpane, individual app preferences, etc. And I have to admit I do sometimes have trouble remembering them. One thing that helps is sticking as much as possible to my own personal convention in assigning them, i.e. giving each available combination of modifiers a "meaning" in combination with the alphanumeric base key:
Eurobubba,
Definitely. Over the years one kind of gets used to certain sequences which… just work!
Thanks.
Or better yet "type text" so you don't pollute your clipboard history (or complicate all of your insert-glyph macros by adding a "delete clipboard" step to each of them).
Thanks. Sure thing. I'm still learning KM and not yet 100% clear about the role of multiple clipboards; and (the need to) switch between them etc. I'm going to get to grips with that next…
When you reach this point, that’s what I meant earlier on when I said (maybe in a different context and/or to another user) “you have to look for a proper concept to launch your stuff” (or similar).
For this, you need an app with proper intelligence. To my knowledge, LaunchBar and KM can provide this. Probably also Alfred, not sure, since I barely use it.
Edit/PS:
I have so many scripts, some of them I need daily, others only once a week or once in 6 months. It would be completely – IMHO – crazy trying to setup a fix hotkey for each.
If you aren’t fine with the typed abbreviation approach (as offered by LaunchBar and KM), you can always also set up different palettes in KM. For example a palette that is only on screen when BBEdit is frontmost. For example.
Following advice from folk here (thanks!), I've already switched to Typinator for as many (text) expansions as I can. I do notice, however, that Typinator cannot (won't) expand 'pwd' in such places as 1Password authentication or waking from sleep at the login screen. Is that just an obvious security limitation that I'll have to learn to live with.
Or maybe KM can do something in that realm which Typinator can't?
Are you speaking about shell scripts? (Launched via Typinator), or just expansions?
Or is pwd a variable of the 1 Password app?
I wrote an article on how you can use Karabiner together with Keyboard Maestro and Alfred. Where you write configuration in a nice DSL instead of JSON. It’s super powerful.
That is an example of what I meant by
@MarkSealey, posts in your thread have managed wonder all over the place, to the point where I think we need to do one of two things:
I would have already done #2, except there are so many, and so many different subjects.
What would you prefer?
Going forward, please adhere to the subject of the Title of this thread. Else, your post may be moved.
(yes, I know, I am guilty of posting off-topic posts here. But no more.)
Thanks, @JMichaelTX; and my apologies!
Please rename it to: Keyboard and Keystrokes, Alternative Solutions - or something similar