Just a freshman runner that needs some help

You ran 35mpw and ran 16:36 so just keep it the same till you plateau.

But how would I get better if I don't do more mileage.

Increase 10-15 miles per year max. So maybe 45-50 next summer for you. Increasing faster than that won't help you much and will probably get you injured. You're on track for a very good HS and college career so you need to emphasize steady progress.

Appreciate it man

Definitely keep doing what you're doing. For one, it's working for you. 16:36 for a freshman is pretty darn good. Also your body is still developing a lot when you're still in highschool. Consistent training is key, let your body naturally develop (growing, puberty, maturation) and you'll keep improving. Eat well, sleep well, hydrate well.

Moving up in mileage to 70+ at a young age would be really taxing on you when you're still growing and it would likely lead to injury.

Get another solid year under your belt at 30-35 so that it's comfortable, then you can start bumping up to 35-45 consistently.

I hit 44 miles this past week and it felt comfortable. Should I just keep doing that?

You can try to continue doing that. Important tips though.

1) Listen to your body. Aches and pains can build up. When you're young and inexperienced you might not know what feelings and pains to watch out for.

2) Give your body time to recover too. It's not about hammering every day. Workouts are for running harder, and easy days are kept easy.

So give yourself a down week sometimes to do lighter workouts so that you aren't beating your legs up.

I mean I have a smart training plan. I didn't hammer myself everyday and I only do hard workouts or long runs before a rest day. My normal runs are about 6:40-7:00 pace, but thats probably going to get faster.

Also, sometimes bumping mileage up doesn't feel bad the week you do it. The following week might feel a little more difficult because of it though.

I would stay at or below 40 through the end of track season. You can bump up a bit more gradually next summer. Your gains in xc will come from 9 more months of steady training, plus improved speed developed during track season. The potential marginal benefits of another 5-10 miles per week are minuscule against the very real risk of 2-3 months of training lost to injury. I have seen kids bury themselves this way, by adding too much and ending up slower.

Look at it this way: keep doing what you were doing during xc, then bump up 10 miles next summer, and you are guaranteed to go under 10 during track and 16 in xc. Bump up mileage too fast and you have a 20-30+% chance of missing training time due to injury or overtraining, having a bad track season, and maybe struggling to run 17 next fall. And the upside is maybe only another 10 seconds off your 5k.

There is a lot of factors other than mileage that influence performance, including genetics and mental toughness.

Overdoing training and workouts in between your mile race pace (4:40 or so) and your estimated 10k (5:30/mile or so) are the primary culprits for 'overtraining', particularly the types of overtraining that lead to long-term issues.

Mileage done at a comfortable pace shouldn't be a major concern, so long as its done at a comfortable pace. If you've upped mileage and you find your body isn't responding well (new aches and pains that aren't just sore muscles, decreased ability to do other workouts or subsequent runs in the week, etc), back take a few days shorter and easier before getting back into it.

Try to do 20 minutes a week as a continuous run around 5:45-6:05 per mile (this should feel like a concentrated effort, but if you get to the end of the 20 minutes and don't think you could do another 10+ minutes at this pace, you're running too hard). If your coach already has you doing a run or workout in this pace range, don't do another.

As a young runner showing some talent, you want to lay the foundation for future success. This means learning to run races and workouts intelligently; learn to be good at hitting paces, desired effort levels, and feeling under control in every workout you do. There is no extra credit for going to the wall in every workout or run you do, that'll just burn you out and diminish long term development. This is also the time to start building a mileage base that will aid you for years to come. Someone else mentioned moving up 15 miles per week per year as a goal, which is pretty reasonable. Next year that means 50 mile weeks, Junior year would be 65 mile weeks, and senior year 80 mile weeks, which is the kind of base mileage that will let you handle much higher quality training when you're ready for it. Setting a goal of moving up 15 (or 20, or 10) miles per week each year is very reasonable, but don't create the expectation that that is what you have to do.

Also, be sure to discuss whatever your plans are with your coach. They can't do their job effectively if you're sneaking off doing mileage or workouts that they aren't aware of.