When Inconsistent Irrationality is Better

I think your (mis)use of the terms "rational" and "irrational" is going to take you down all sorts of misleading paths here..For example scientists use Newtons equations of motion and gravity in all sorts of circumstances. They know that the calculations would be marginally more accurate but much much much more complicated if undertaken using the equations of GR and SR.Wouldn't it be irrational for them to do this if Newtons calculations provide perfectly adequate and practically workable answers?