Maybe it boils down to how often I actually use it: if I know I won't be shooting for a week or two, take the lens off?
Seriously, I think you're worried about nothing. If there's going to be torque on a lens mount, it's more likely to occur as you swing the camera around while you're using/carrying it than when it's sitting in a bag. Any current Canon body has a lens mount that's designed to take any EF lens. If a lens is so heavy that it would put undue stress on the lens mount to support the lens by the camera body, Canon would provide an alternative means of support. They do that for the supertele lenses (strap lugs on the lens barrel, non-removeable tripod mounts), the lightest of which is the EF 400mm f/4 DO
IS at 68.5 oz (1.94 kg), but not for next-heaviest lens in the lineup, the EF 28-300mm f/3.5-5.6L
IS at 59 oz. (1.67 kg). So, the inference is that a lens weighing 60 oz. or less will not place undue stress on the lens mount. The 24-70mm, despite sometimes being referred to as the 'wedding brick,' is a mere 33.5 oz (0.95 kg) - nothing to worry about in terms of stress on the lens mount.