What methods are not effective in preventing heat stress and stroke?

Hmmmmm? We don't prescribe non-effective methods. Prevention of heat stress or stroke is built around, ventillation, evaporation, hydration, and proper rest. One must drink large volumes of plain water (or may use "gator-ade type products), get as much breeze as possible for evaporation (cooling process), and have appropriate rest. Removal from the source if possible if working outdoors, enclosed area.
What a question! Are you planning on getting heat stress or heat stroke? Why would you ask that question? You should be asking what should be done to prevent those conditions. You have a major streak of pessimism. Instead of looking for problems, you ought to be looking for solutions.