21.—(1) Subject to the provisions of paragraph (2) of this Regulation, a child shall not take part in performances or rehearsals to which this Part of these Regulations applies on more than six consecutive days.
(2) Where in any period of seven days a child takes part in performances or rehearsals to some of which this Part of these Regulations applies and to others of which Part V of these Regulations applies, he shall not take part in such performances or rehearsals on more than five days in that period.