There is no time limit anymore for how long you can leave TQs in place. Removing a TQ is not a current TCCC task (Just checked the DoD courseware). I've seen permanent damage after only a few hours in one individual and an extremity completely recover after 24+ hours of TQ placement. We finally realized there are too many other factors in medicine than a watch. Good wound care (bleeding and infectious control), medics who know their shit, and lots of replacement fluids/blood cells/meds are what's saving extremities now. Good pre-hospital care is key.