The reasons for hot restart problems can vary greatly depending on the fuel system being used, the year, make and model. The newer the system the less likely the problem. Newer systems have less mechanical problems. Older more mechanical fuel injection and carburetors have more problems. If you have a problem, the fuel being sold today seems to exaggerate the problem. If there is any common denominator it would be the fuel. That being said, a fuel system working properly should not have a hot restart problem. The system used on the V-8's is very different from the 4 cyl and among the 4 cyl, on the older ones, they use the mechanical K-Jet system. Each has it's own causes of hard hot restart. On the V-8 if you do not achieve a fast enough cranking speed the motor will not start. The ECU is not getting crank pulses fast enough. Maybe those that have replaced the crank sensor and noticed an improvement set the gap properly when they installed the new one and the old one was set a little wide.