I've been interested in getting as much on one layout as possible, but in a logical way to make it easier to learn and remember. Right now I can't do it all because of limitations on what we can change. I've posted to WT about it, hoping there isn't some built-in limitation they can't avoid.
Meanwhile, I thought I'd post my ideas here to get some opinions. The whole things boils down to the need to be able to go into the number lock, edit lock, or (I hope) an eventual media lock mode but have both the present main layer but add in a green layer.
Right now on the number layer, the 15 keys are taken up by 10 numbers, a decimal point, and the four main math operators. Anything you add needs to go on the left blade which means you need two hands.
Now suppose you can edit the green layer in number lock mode. It seems it would be fairly intuitive to put the plus key on the main layer, but the minus key on the same key but use the green layer. Same with multiply and divide. Now you are only using two keys for the math - fewer keys to remember and simple to think of the green layer as making something smaller (minus or divide) - but other logic could be used.
With the two freed up keys, we can do what some like - include the normal number keys across the whole top (sometimes if you just need a quick digit, it can be easier to reach out and hit a number you actually see). This means adding another 6 to the right hand - but you still have one key free on the main layer. Maybe an equal sign. Or make the decimal key have a green layer equal sign. Now you still have a free key - possibly a combination for $ and %. Or maybe open and closed parenthesis. And remember, you still have the number pad keys you can do something with on the green layer. Suddenly it is rare, if ever, that you need both hands for number operations.
This logic can apply to editing. Forward and back on letters, words, or lines could be handled with half the keys. One for moving forward while the green layer reverses the direction. Undo, redo could be one key. Cut or copy on one key.
Likewise with media. Volume up and down just one key. Fast forward and reverse is one key.
Now if you have no need to have some of these things accessible at the same time, the consolidation this would allow may not matter to you. But for me, I could combine all the editing stuff on one hand with all the media stuff on the other and still have keys left over for other things. Heck, since the symbols for editing and for media are quite similar, we could have editing on the main layer of the right hand and media for a green layer.