The Brick Institute of America recommends that wall ties be embedded to at least half the thickness of a wall when solid units are used. What should be done with hollow units?
ACI 530.1 states that ties should be extended halfway into the face shell. Therefore, the tie will engage less mortar in hollow masonry than it will in solid masonry. For this reason, I would recommend using more ties in hollow masonry than you would with solid units. An alternative is to grout the cells of the units where ties are embedded.