Every teaching method you can think of has been tried. What you are describing is called scaffolding with manipulatives which you can find dozens of for maths. Schools have also tried making worksheets catered to multiple skill levels within the same classroom.

The harsh reality: most children infamously still have a hard time even being able to tell the time on an analogue clock. You can try every method under the sun but if a child has a hard time understanding a system with two different base numbers it is usually because they just don't have the capacity. All the handholding in the world isn't going to change that.