Supposing, hypothetically, that someone receives a beautiful gift of a 10 gal copper still, more for their home's aesthetic than for the utility expected out of it. But say the receiver decides to do a sugar/molasses mash based on a random web search, &, while it's fermenting learns all she's ever known about distillation via the internet....resulting in a run that yielded 17 jars filled to 200ml, with the first jar's worth discarded as the forshot. Now, she's read that heads are comprised of the 1st 30ish percent, the hearts are comprised of the following 30ish percent, & the rest are the tails, & this formula is scaleable. She has hydrometers (yet never used them). So with that...is there a certain mathematical formula that can be used to differentiate by volume, heads from hearts from tails? If not...is there another definitive way?

Also, she's noticed that some of her favourite spirits have been distilled upwards of three times. Would that be worth doing on this initial run?

Thank you kindly to all who are gracious enough to reply! Any thoughts or advice would be greatly appreciated.
Regards,
Toast