"Classic floc really only works with regular cow milk" does "classic floc" refer to the multipliers suggested in recipes?
All recipes are formulated to work for an individual situation. The majority of people use cow milk with moderate solids. Whenever you go outside of those basic parameters, the recipe needs to change to achieve similar results.
rennet impacted the flavor.
Residual rennet quantity is a primary agent in building flavor precursors because it keeps breaking down proteins as the cheese ages. So amt is vital. More protein in milk with the same residual rennet = less flavor precursor formation. So for ND milk, helps to use 10-20% more rennet. But that influences coagulation, as it's already high solids, so it's a delicate balance.
why am I even using floc timing?
Because once you dial in the rennet and floc for your milk profile, it will help you achieve consistent results for you, despite milk variability.
how do I choose what multiplier to use on each recipe? Is there a rule of thumb?
Yes, fr soft washed rinds, it's 2.5-4x. The moisture in the final cheese is more than just the multiplier, but it does help to achieve the right target.
means I'd be cutting after 16 minutes.
Think about the rate of gellation. With more rennet, the tangential speed of gellation is faster. So 16 mins with 10% more rennet does not result in 10% more set... more like 25% more. So by the time you cut and heal and start stirring, those curds will be able to retain much more moisture.
a longer set time and I can increase my multiplier even more but won't that make the curd harder?
harder curd = more moisture retention = more moist cheese.
do you mean the stirring or time stirring? If I stir less but that segment of the make is still the same length of time the curds will clump to the bottom. Do you suggest gently stirring only enough to keep them from clumping?
I'd have to see and feel the curd to tell you. less stirring and draining in molds and less vigorous stirring both result in more moisture in the cheese.