Is the failure to visit relatives—such as paternal uncles and maternal uncles—on regular days, and sufficing with visits only on special occasions and holidays, considered a severing of kinship ties?

It is obligatory to maintain kinship ties as much as possible, and these ties are established by what is customarily considered to be maintaining them. The degrees of maintaining ties vary. Visiting is not the only way to establish these ties. If visiting is difficult, then maintaining ties can be achieved through communication and inquiring about their well-being, and they should be excused if they express blame.