What about the triple jump?
The triple jump is pretty tricky. If you were to research which foot to use in your first takeoff you find a large number of differing opinions. Again, this should mostly be about the comfort of the athlete. But, there are also some other considerations here that need to be part of the equation.
Consideration #1 - The amount of "pounding" the athlete's legs are taking. If an athlete is a long jumper AND a triple jumper they may want to use different takeoff legs/feet to preserve the health of their legs to the best of their ability. Personally, this is NOT the route I have my athletes follow, but it definitely is something to keep in mind. I would only use this one in severe cases (of leg discomfort and/or injury).
Consideration # 2 - Use the same leg as the long jump because the athlete has already expressed this to be their "comfort foot". You spend two-thirds of the triple jump taking off from one leg - why not use the one that is most comfortable (and most likely stronger)? Like I mentioned in the first consideration though, you must keep track of the "pounding" the chosen leg takes, and never jump the athlete in both jumps at practice and/or meets (unless you have planned a very low impact workout).
Consideration # 3 - Coaching observations. Coaches need to understand what to look for when training their athletes. If a coach is working on bounding and realizes that a jumper shows a better ability on one leg vs. the other, this is incredibly noteworthy! The coach might suggest that the athlete make sure to use that leg/foot while performing both the hop and step phases. Coaches, it's your job to be observant in everything your athlete does. Pay close attention and make suggestions when necessary.
Consideration # 4 - Overall coordination, hip flexibility, and strength of the athlete. If there is a lack of strength, coordination, and/or flexibility in a certain leg I would suggest using that leg to perform the jump phase. Strength, flexibility, and coordination are SO important in the hop and step phases that you will want to use the leg that encompasses most of those focuses. I am a firm believer that the step phase is what separates the great jumpers from the rest. Without performing this phase properly athletes can only hope to be average. For this reason, finding the proper leg is extremely crucial to the overall jump.