@Zabobon: in other words, taking the most simplistic approach, one does not even have to think about what shortcut/hotkey to use for a new macro. Just implement anything that takes your fancy.
And when it comes to activating it, Conflict Palette is there to not only show which other macros share that hotkey, but it even allows you to pick one from the list.
Well, not quite...
I use patterns of hot keys for different tasks. So, in my case ⌃⌥⌘ and a single letter is when I want to "go" somewhere like to a website or to a folder. So, ⌃⌥⌘G for Google or a folder beginning with the letter G.
I use ⌃ and a letter when I want to open an App. So ⌃P for Photoshop and Pages and Photos. And ⌃C for Calendar and Contacts and Chrome.
But for shortcuts inside individual Apps I use specific shortcut keys and palettes. Here is my Palette for Photoshop for example. (This is a regular Group Palette not a Conflict Palette).
You'll notice that the above Palette lists the shortcut key. So, this in itself makes if easy to learn the keys for things I do a lot (which was your original question that started this thread).
Everyone will work out their own system - there is no "right" way to do this stuff - which is one of the many things that makes Keyboard Maestro so powerful.
But it's great to get insights into the ways you are all doing this.
I put it very simplistically, and in practice you, and others here, have developed a system to categorise the hotkeys, even when using the Conflict Palette.
But at the end of the day it seems to me one does not have to worry about conflicts, therefore about duplicating a hotkey, because the Conflict Palette assists in that. categories notwithsanding.
I know you are asking @JMichaelTX but allow me to butt in. I do all my text expansions on Keyboard Maestro. I dropped Text Expander in fact. I am told, Peter Lewis himself says not to load up to much on expansions: it takes up a lot of file space or something I don't remember. However for the number I have it works fine.
@tudor_eynon: thanks for butting in. The question was directed @JMichaelTX because he wrote such an expansive reply, but that does not mean someone else is not allowed to answer. At the end of the day what counts is to get an answer, which you provided perfectly 
I am using Espanso myself, a very light-weight text expander which apparently is quite powerful. I say apparently because I use it for only very simple expansions.
Anyway, KM could take that over.
Thanks for mentioning Espanso @Klaas1. I’ve not heard of that one before and it looks worth examining!
I found palettes work really well. I rely on them heavily now rather than shortcuts. Well obviously I have a shortcut to get to the palettes!
@tiffle: yes, Espanso is worth looking into, and the dev, Federico Terzi, is very helpful. And it's free and cross-platform.
For a few, specialized, complex cases.
In general, I use Typinator, which I highly recommend if you have a lot of text expansions.
Another alternative is Shortcutdetective. I’ve found it to be very useful to figure out which application is capturing the key binding .
I generally follow the "keep shortcuts in categories" approach that others have mentioned. But two other options that I don't think anyone has brought up:
Add an "Active Status Menu" trigger to the macros that you use infrequently or otherwise aren't ideal for keyboard shortcuts. These show up in the Keyboard Maestro Engine menu in the menu bar.
If you are also use Alfred (which I think complements KM very well), try the Alfred Maestro workflow, which creates a keyword to search your Keyboard Maestro macro by title.
