Typically 3 manga chapters make one anime episode if HM arc had continued we would be left without any manga material . The only long running sucessful series which has done this fine rope walk is One Piece . But thats a diffrent issue alltogether
Regarding where I would interject this arc
* Vizard training with Ishida regaining quincy powers shown before or
There is another good reason the the Bleach Team rushed in to compete with shippuden team to air manga materials . Regarding discontinuity of the arc watch its as a movie or ova you will enjoy it more