I love to share the little I know, this is how I cut my pálinka.
For (non-geisted) true fruit spirits - like pálinka - and for geisted (fruits macerated in neutral alcohol 10:2) - like schnaps - it all goes pretty much the same way: dilute the low wines to 20%ABV. 20 because at 25 it is difficult to separate properly, at 15 more methils stay trapped.
It will not foam, pot can be filled to 90%.
The first 0.5-2% should be thrown out, it is filled with most of the acetil-aldehide/ethyl-acetate the low wine contains. If one raises the temperature of the pot slowly while making a fruit-brandy the most methyl-alcohol can be driven out. If you hurry, some of it will stay in the hearts and it will not air out, it will stay there.
I switch to the hearts when the spirit start to come at 70%ABV, before that I collect every 100-150ml in separate jars, that have a paper napkin on top of them as cap, held there with an elastic ring. 24h later I dilute a tsp. of them with same amount of water and decide that does it give to or take from the quality of the heart. The sharp smell can disappear from these samples, but it takes time. This was our fruithead.
I collect hearts down to 45%ABV, because I work only from freshly fermented stock that I know and I cook them after a day or two after they are ready. If something is wrong, the hearts can end at 50%. At the first sign of a bitter taste (that is not an alcohol-like bitterness) cut, and start the tails. The part from 45-41 is what I always throw out, it is a lazy, featureless, sluggish part in most of the fruit brandy distillates. Don't ask me why, but my pálinka is much more crisp, lively and has a more pronounced loud taste when I drop that section.
From 40%ABV, collect to 100ml jars again, around 32%ABV usually there is a very aromatic slice, but it is backed by a little bitter unusable part from below, and this is where I use to stop distilling, at 30-20%.
As for the numbers: today I distilled 15L low wines of black cherry. In my black cherry pálinka the traits are the "high" cherry aromas, and only a very little balancing "deep" marmelade honey taste. Cherry is generally a delicate fruit that needs a refined approach in distilling, and it can be achieved with raising the pot's temperature very slowly and a cold, cold worm.
Preshot was 50ml, then I collected 6x100ml heads, took about 3800ml heart (65%ABV), and finished with 2x100ml tail.
It took nearly 6 hours, about 4 drops / sec. Yes, plum and apricot is made much, much faster with very good results.
So, my two cents in a nutshell: collect those heads, air them out, some of them are the golden ticket in blending "high"-aromatic fruits like apple and bb. Drop the lazy part out and spice the blend with a selected little non-bitter jammy part of a tail.
Good luck!
Edit: after blending, pour the spirit in a clean bucket and dilute with the cleanest spring water (or distilled water) you can find, and let the water down on the side of the bucket in a very thin stream. If you hurry the brandy can become misty, and it can take (stressful) weeks to become clear. My red cherry (which is a sharper, crispier tasting spirit compared to the bc, it also has a marzipan aftertaste because of seeds) and my black cherry pálinka is 45%ABV, strong enough for a nice sensation and light enough that the fruits kick in full strength. This is the strength I truly recommend for fruit brandies, except for geisted raspberry, it is better at 42%.
All fruit brandies must age a few months, after six months their taste will be harmonized. As for pálinka, a few piece of fruit inside the glass can enhance the "wow" factor, especially ladies like it, we call it "ágyas pálinka" (means: emBEDded, "ágy" means bed, but "ágyas" also means concubine).
Blending the pálinka with a little honey, it can be called "mézes pálinka".
Only the close-to-neutral smelling pálinka (like mulberry or elderberry) use to be aged in barrels made from robinia-, mulberry or fruittree pálinka-barrels, and only to acquire a mild colour and a very light wood-taste. No serious oak-aging is usual, even less traditional.
Mulberry-trees are still near every horse-stable (or/and piggery/hennery) in farms around these parts (the Alföld) because it is believed to deter horseflies. Often one can find a smithy in the close area of a mulberry tree, it is very annoying to fight with flies while you hold a red-hot piece of iron in one and a heavy hammer in the other hand.
This is a useful tip, you will know where to find a blacksmith when your horse kicks off its shoe, as mulberry trees are huge and high and our lowland is flat. Many years ago mulberry-leaves also were collected and given to feed silkworms, and the silk been trade for import goods. When the fruits just start to ripe be sure to bring a net under the tree and collect the ripe fruit, as overripe mulberry does not have a pleasant smell (to say the least), and it attracts flies badly.
