IMO the concept of a "clean break" is just to make sure you don't end up with a fragile curd that shatters easily.... There is no way that a Flocculation multiple of 2.0-2.5 results in a clean break, and in my (limited) experience even 3.0 can be a bit sloppy.... I would say that you need a Floc. multiple of 3.5-4.0 to get a clean break, at least that has been my experience, with a P/H milk and cream mix....
This doesn't mean you can't make a successful cheese with a Floc. multiple of 2.0, but that is because you will also be cutting the curds smaller anyways.... I have been trying to come up with a "formula" for curd size in relationship to the Floc. multiple, but the best I have been able to do so far is a range.... I find that a cheese that calls for a Floc. multiple of 2.0-2.5 is nearly always cut to 1/4", and ends up at Barley to Rice sized grains once cooked.... If the Floc. multiple is 3.0-3.5 the curd is usually cut to about 3/8", then after gentle stirring ends up bean sized, and once cooked about pea sized.... When the Floc. multiple is 3.5 to 4.0 the curd cut seems to be 1/2", with the curds starting out as hazelnut sized and ending up bean sized after cooking.... I haven't done anything that requires a Floc. multiple of 5-6, but what little I have read indicates that seems to be related to 3/4" to 1" curds, or ones that are just carefully ladled into the mold....
One thing I have started doing lately is cutting the curd in two stages.... I do the vertical cuts, resulting in columns, then rest 5 min. during which time I gently move the pot each minute to make the columns wave around and start losing whey.... I then do the horizontal cuts, resting another 5 min. during which time I move the pot each minute in different directions, including turning it.... This is in effect "stirring" the curds, but the only thing they touch is the whey and each other.... After this my wife takes over, she has just the right "touch" in turning over the curds gently with a slotted spoon, barely moving them around in the pot for the first 5 minutes, just bringing them carefully to the top.... After that, the curds are much less likely to shatter, and by the end of 15 min. of stirring (during which time we may or may not be raising the temperature, depending on the recipe), the curds are firm enough, and strong enough, that they don't shatter any more, unless you are being a brute....
We are trying to develop a "systematic" approach in our cheesemaking, where the steps are interrelated, and distinctly different depending on the results desired.... Yes, to be sure, some individual recipes seem outside the "norm", but trying to understand the basics of how the Floc. multiple and curd size relate to the finished dryness of the cheese seems to be important.... and something we are striving to understand.... Any comments, particularly if you can see a glaring problem with this approach, are welcomed....
Bob