Ah, hey there. Deep calming breath please! It's a gray, snow-dusted Saturday morning here in the landlocked middle of the USA. I'm visiting my favorite thread and hoping to find some fun stuff to lighten my day! In an effort to bridge the gap and return the conversation to a more mellow place, here's my 2 cents worth:
On one hand, I see Susie's point. There are a lot of newish soapers on SMF, many with poor math skills. Like Susie, I try to steer inexperienced people to reliable solutions that don't require a pencil and calculator, even if I know calculator-based ways to solve the problem. So you'll usually see me talking about how to use the SoapCalc or the Summerbeemeadow calc rather than how to figure stuff by hand. Or, what's worse, coding formulas in a spreadsheet! For math-phobic or inexperienced soapers, I think a ready-to-use calc is by far the best choice.
On the other hand, I see Fuzz Juzz' point. I am comfortable with the calculations needed, and I have created and prefer to use my own personal soap calc on Excel so I can tweak every nuance of the recipe calculation process. I don't know that I'd say I "wing it" exactly, because I usually have a science based reason for my tweaks. But I really do get the point of what you're trying to say, FJ -- I'm trying to refine the recipe calculation process to get more reliable or more understandable outcomes. I don't know that my results are any more accurate than if I used SBM or Soapcalc, but my soaping doesn't seem to suffer from my arrogance in preferring my calc to someone else's.
My concern is that, even for me, calculating a recipe by hand will always be more prone to math or calculator error than using a calc, whether it be my own spreadsheet or someone else's calc.
And even if a hand-calculated recipe is mathematically correct, the results STILL depend on my choice of a specific saponification value for the fats and the purity of the lye. Without a chem lab to test every batch of fat for its saponification value and every batch of lye for its purity, we're still at the mercy of the published information with all its variability.
I suspect that most people are going to continue to use Soapcalc or SMB rather than make their own spreadsheet or calculate by hand. I sure hope we can come to some conclusions about these calcs to help people understand the differences and understand whether the differences are important or not.