The restoration of old sash windows is time consuming and difficult to do properly.
When I restore windows I strip the paint back from the sashes and the window frame to the old wood so the sashes run free.
It would be far easier and cheaper for me to buy new sashes and install them like most of my competition do instead of restoring the old ones.
I could use cheap fittings on the windows, my customers would never know but I don't.
There are plenty of shortcuts I could take to get my jobs finished faster but I don't take them.
This is the difference between someone like me and others.