A technique I learned from an old mechanic 60 years ago was to tightened each bolt using three to four cycles at each step. The cycles are tighten to the specific torque, back off, tighten again noting if the wrench moved further than last time. If it moved a noticeable amount repeat. What is happening is that the high spots on the threads both on the bolt and block are smoothed out. When re-torquing after several heat cycles I find little to no difference.