The answer is compromise.
I planned a layout for some years before actually making a start on building it.
Even at that stage I had to make some compromises to fit available space.
When I started building the layout I realised my manual skills
were not as good as my designing skills.
I reached the point of giving up, but, thanks to encouragement and suggestions
from RMWebbers, I made some changes and carried on building.
What I've ended up with is not what I planned, it certainly wouldn't pass
rivet-counter inspection, but I have somewhere I can run trains and enjoy.
If we look for perfection it will never happen