Great questions and ones I am still trying to figure out! I am grateful that I live in a state where indoor is not an official season. Our kids typically run XC, take a week off and then 1-2 weeks of light/partial running. They run all winter, but we don't have an official indoor season so must run about 1-3 races between December and March (local road races or hop in an indoor hs meet hosted by regional colleges). Track is March-May and then kids take another week off in June (usually right after track, but sometimes we have them wait and take that week off if they have a family trip scheduled). Freshman/sophomores would run anywhere from 5 to 7 days a week, between 20-35 miles. Super motivated and healthy juniors/seniors that are fully through puberty have run as much as 55 mpw in our program, but the norm for varsity upperclassmen is 40-45.
I agree wholeheartedly with this! We notice challenges when girls hip shape change, mainly because they start dealing with little aches and pains as a results of the growth. We tend to back off mileage and have them use that extra time at practice to do additional strength/prehab work. Almost every 4 year athlete has a season where they are impacted by this, so we talk openly about it and they know to expect it and that we'll handle it. Most seem to have that growth sophomore year of track, but it does vary.
For girls that are having more extreme changes, we have also changed up their events in track significantly so that it's harder for them to compare and/or put blame on themselves. A season devoted to the 800 where they get to run some 4x400s and only the occasional 1600 can be a fun challenge and I like the emphasis on speed helps their long term development anyways.
I also think coaches have a responsibility to help athletes set realistic long term goals . We try to set short term process based goals rather than long term outcome based goals. For example, our goal this summer is focused on the long run. We want our newcomers to be able to run for 60 minutes by the end of the summer and our returners to be able to run a specific 8 mile long run route at our July team camp. Kids have way more control over that than running a specific time at a specific race.