ko bet ramp single deck

[arrando]

In the book, it says the ko 1-5 bet ramp should be be 2u at +2, 3u at +3, and 5u at +4 or higher. I'm looking to only spread 1 to 4 though. So would I just drop down to 4u at +4 and leave the other two the same?
Also, does anyone know at what depth do you not have an advantage anymore at +2?

Thanks