Here's one of the main reasons your old Stanleys don't perform as well as new LN's and LV's.
I've rehabbed a few dozen of these old Stanleys now, and have yet to see even the wide smoothers that weren't used to joint boards, creating a hollow right down the center of the sole. If both the sole between toe, the front of the mouth, the heel and the back of the iron aren't dead flat, it's impossible to take a perfect shaving of equal thickness throughout.
Here's an out-of-true #4 1/2 sole where sanding the blued sole shows high spots everywhere except around the sides of the mouth:
Here's the same sole after considerable sanding with high spots remaining at toe and heel...you can clearly see this smoother jointed a lot of boards:
And here's the completed sole....flat enough to perform well, but still with small high spots remaining at toe and heel:
Sanding is done using 60-grit wet-or-dry lubed with WD-40 on the jointer table, sanded until sufficiently flat then finished with grits in series from 80-150 grit.
““Perhaps then, you will say, ‘But where can one have a boat like that built today?’ And I will tell you that there are still some honest men who can sharpen a saw, plane, or adze...men (who) live and work in out of the way places, but that is lucky, for they can acquire materials for one third of city prices. Best, some of these gentlemen’s boatshops are in places where nothing but the occasional honk of a wild goose will distract them from their work.” -- L Francis Herreshoff