To mirror or not...

Wanted to post about a small matter in, what I would think applies
across the board to any 3D modeling software, not just Solidworks, and
that is the subject of "Mirroring". As a rule of thumb I try not to
mirror when I can make it just as one surface. This holds true way
back to my Alias days on SGI computers. But lately I have been hearing
some conflicting theories and speculation about what exactly is going
on behind the scenes with regards to SW.

If I think of a car body, and the way it would be deigned, the doors
or items that has a specific left and right half will be ok by way of
using a mirror. But the Hood, thee roof, the bumper...etc should
produced with as much if a single surface as possible. Maybe this is a
pet peeve of mine, but I can't stand broken surfaces if they don't
have to be.

Getting rid of of line and arc segmets when possible by using a fit
spline over it is one proposed method to keep surfaces cleaner. I have
also seen some models where left 1/2 is done, mirrored over, and then
recreate any surfaces that fall into the above category.

TIA