Yosef Karo

“ According to the ר׳י, even if the entire branch was severed but there remains enough thread in the tassel to make a loop, it is Kosher. The world custom is according to Rashi. In a difficult situation, one can rely on the ר׳י. ”

“ According to our practice - which is to be careful when making Tzitzis to place a mark on four of the ends in such a way that these four ends are always on the same side of the knot, and the four [doubled] ends are on the other side - if two ends tear off on the same side, the Tzitzis are still Kosher, because certainly these are two [different] strings, and each one still has its second end which is more than "long enough to tie." ”