For marketing purposes of course...
if you want to outsell competitors 5.1 model you need a 6.1 model.
If the competitor comes up with a 3D multimeter you need a 4D multimeter to outsell it...
Your signature reminds me of an anecdote.
We were trying to run basic flow code with matlab.To do so,we simulated a curved wall,defined by a nicely-given function.
Check with the HP calcs,ok.Run the code...something strange on the outer wall,right in the final part where troubles can arise..but that problem shouldn't have come out.
Hand check the functions,the discretizations,calc and draw some flow lines by hand,everything ok.
It looked like that part of wall was and wasn't there.Open the variable table and check them all,everythings' fine.
Then i had a lightning.
The wall function was discretized in points,and matlab was reporting them as discretized values.
But the variable editor just showed the first 4 or 5 digits,not the exact value.
So 99.99999999 was displayed as 100.0000,which is nice for a cake recipe,but not for the boundary conditions checks who red "fluid" instead of "wall" on those points because 99.99999999<100.0000
So there you go,a true case when a 1E-8 can waste you an afternoon.I still have the hand drawings somewhere.