Good question - I am not a professional so I am not always right - but here I go anyway - - traditionally - bowlers have been taught to do 6 sides to keep the ball as round as possible - at the factory machines do most , if not all of the sanding - I think I saw a vid of the Ebonite plant where rows of Haus machines were in use. I think the first cut was done on a lathe - then another machine made the ball smoother then the ball started the final finish process in the Haus Machine area - we know that if you don't skip grits while sanding you will end at the desired grit level and we know skipping grits give a different final finish - and we know if more than light pressure is used, low grits remove surface very, very, fast - water volume makes a large difference in the cutting efficiency of Sand paper, Abralon, Mirlon or Scotch Brite. Visually you can see the difference as less or more sheen - balls from the factory finished at 4000 have virtually no sheen - this is evidence of a really clean cut.
How hard is the surface of your ball? Softer balls get cut much faster and have a different look when finished - remember, you can't replace what you cut off.
When I do a resurface - 6 sides at every grit 30 to 40 secs per side - very little pressure - depending on how fast the ball cuts. For a simple surface renewal I start one grit below the target grit - for a quick touch up I do 4 sides at the target grit.
Charlest is the surface guru here and has posted many, many times - perhaps a search through his posts would help you -
I am not sure of the current thought about doing 6 sides -vs- 4 sides - I think I remember seeing a vid produced by a spinner manufacturer that demonstrated using 2 sides only for each grit for full resurface jobs.
I know, I did not give a cut and dried answer - we help as much as we can, but in the end the proof is in how the ball rolls and - what you did yourself - to get it there.
OnlyBowling