This may be a basic question but do manufacturers make a standard length door knob spindle and then expect us to cut it to the size we need? If not, I must have skinny doors in my house.

Thanks for the help,
swomen

Your typical locksets are sized for modern doors which are normally 1 1/4" to 1 5/8" thick.

Older doors were often only 1" thick or less in some cases.

Unless your home has the older style door locksets with a square key box on each side and knobs that unscrew from both sides and a center rod, there is really no way to "cut" a modern lockset to fit a narrower door.

The older style locksets allow you to set the depth of the rod by screwing it deeper into the knobs. This rod can be cut if necessary.

If you are describing the square shats on old mortise in locksets, a few shim washers on the rosette trim takes care of it.
You may have lost the original shims o they have worn out