There was a nice thread about string spacing a couple of days ago, some of the things mentioned seemed to have surprised several people. It's an interesting read especially the details Joel Hooks added:
Some personal comments for 5 string banjos: when I started making bridges a goodly while ago I always got tangled up looking at the wrong darn stripes on the ruler that measured only in inches. Heck with this, I switched to a ruler marked in millimeters and that worked out a whole lot more reliable for me. It was kinda unusual at the time as string spacing was measured in inches and fractions thereof. Over the years though, it seems several bridge makers have adopted millimeters as well.
As you can see in the post I linked to above the term standard string spacing is quite open to interpretation A bit of a problem with that term though: many people seem to be under the impression that any other string spacing should not even be considered because, "no way that could work for me or for my banjo."
In general, a banjo neck that is approx 50 mm wide at the heel/pot can easily accommodate string spacings up to 48 mm wide without the strings spilling over the edge of the fret board. Practically speaking, the safe max limit for most banjo is 46 mm as wider than that often results in intonation problems. Oh, Framus, or Contessa, banjos need narrower than "standard" spacing because of their narrow necks: 38 ~ 40 mm is perfect for them.
The 46 mm spacing by the way, I started marketing that spacing almost 20 years ago, works out real well for clawhammer (extra wiggle room for the thumb) or for 3 finger style pickers with thick fingers & thumbs.
Which string spacing is best for you, and your fingers, is quite easy to figure out. By all means, check it out as it could easily improve your banjo's playability. Make a few dummy test bridges, carve them up with the common string spacings and let your own fingers tell you what's best for them. Making a dummy bridge is real simple, here's how on my own website:
I needed string spacing at the bridge of 1 7/8ths from 1st-5th string, and a 1 5/16th nut width. I had to replace the narrow 1 3/16ths Huber neck I had, and have a 1 5/16ths neck made. Everything is fine now. No more narrow bridges or necks for me.