I don't have a pH meter, so it is possible that the acidity levels were higher than optimal. Also, using ice cubes of starter could allow one to adjust the ripening period, although in this case my notes indicate it was only 15 minutes. However, as I add the cubes when the milk is cold, they are thawing and working during the time it takes to warm the milk up as well, and that's probably another 15-20 minutes. I'm not sure the floc time is the one I would adjust, for, as you mention, that's important with respect to final moisture content. Rather, cooking times, ripening times, and determining when it should go into the brine are probably points where one can adjust things. Use of pH meter to determine these "on to the next step" points shifts one away from time based make protocols (much like using the floc method moves one away from a clock based cutting time). I would base things on pH, but, alas, I am meterless.