A method operates a facility, which serves for the continuous production of multiple gang runs for forming individual signatures or signature packs from which type-specific print products are made in a downstream print further processing machine. An endless web is the basis for the formation of these multiple gang runs. The endless web, in the non-folded state, is imparted complementary handling by facility-internal means according to the following criteria: i) in a 2-gang run, the individual signatures or the folded signature packs are only deflected in a second longitudinal air folding station disposed downstream of the first longitudinal air folding station; and ii) in a 3 or 4-gang run, the individual signatures or the folded signature packs are additionally folded in a second longitudinal air folding station disposed downstream of the first longitudinal air folding station.

Provided is a saddle stitch folding apparatus including: a stitcher unit; a reel support unit configured to support a reel rotatably about the axis with a support shaft being inserted in a through-hole formed in the reel; and a rotation detecting mechanism configured to detect a rotation state of the reel, and the rotation detecting mechanism has an adhering member that is rotated while adhered to a bottom face of the reel, a rotating member having an insertion hole inserted in the support shaft, and a rotation detecting unit configured to detect the rotation state of the rotating member.