Feature Request: Center Two Thirds or Center Three Quarters
Great for those of us using an ultrawide monitor.
I don't mind adding these in at some point, but they are trivial to add as a custom shortcut:

Ah! I didn't understand what "Custom Shortcuts" meant. This is exactly what I was looking for. Thanks!
I tried incorporating a W: 1/4 and H: 1/2 for 4x2 grid but couldn't quite grok the docking position for the inner sections.
@akwan You'll need custom docking positions:

For anyone else interested specifically in eighths- going through the setup for a new computer (and coming from the OSS version) - I just realized that eighths are part of the default setup and it's not necessary to create a custom shortcut for them. But the example above is great for mimicking it (e.g. to create a joined inner upper, joined inner lower, etc).
Another reason more defaults would be helpful:
I have a custom shortcut set to Center / .7, .7
I have Repeated Commands set to Cycle Through Displays, which I prefer. Cycling works for all the builtins, but not for my custom shortcut.
The poor window, all alone floating the the void of the first monitor while the party's moved on to monitor 2...