Those are some good ruck times. Pretty similar to mine. Are you jogging at all or do you just have a large stride? When I met with some CSOs and talked about my training they told me to slow down a bit. I was averaging 10 minute miles with my pack but most of it was a jog. They told me there wouldn't be a need to jog with a ruck in A&S and it increases your chances of an injury. Also I don't know if it is a mistype but is there an hour and thirty minute difference between your 5 mile and 8 mile?