Back in my cross country days. We ran high distance over the summer to build our base. In season Sat was a long distance day, at least 10 miles. Sunday alternated between off and a 4 mile bridge run, basically interval training. During the week was usually a total of 6-8 miles.
Typical day was 2-4 mile warmup. then stretching. 2-3 mile interval training(could be quarters, sprints, fast 5k, whatever) 1-2 mile cool down, and stretching.
Main thing we never did the same thing twice in a row or even week to week. Our coach was always changing things up, so you never got bored.