It won't make things more accurate - in fact it'll make things LESS
accurate. :-) But that might be exactly what you need.

The spreadsheets I write contain mixtures of numbers and I don't turn this
option on because I might not want to display all fields to full precision.
However, if you are dealing with spreadsheets that are mainly financial in
nature, it might make a lot of sense to turn this on. At least you
shouldn't have rounding problems due to undisplayed information. You would
need to be careful to display each numeric field to the appropriate
precision to ensure consistent results (i.e. don't use "General" format),
but I can see that it might well be a good idea.

It would be much nicer if this were a cell attribute (or a format switch at
cell level). At the moment, it's a bit "scatter gun" for my taste.