I am a big believer in staying in touch with all speeds all year. The volumes at each speed change from phase to phase. The amount of anaerobic work is relatively low until 6-8 weeks from the ultimate meet outdoors.
Very rough rule of thumb:
November - Run without any structure. Enjoy running as an activity rather than as training.
December - Ramp up towards goal mileage for the winter. For those that have been running regularly in November add in Hills once per week, but let them rest in between hills as much as they want with the volume of work on the hill no more than 5% of their weekly mileage. Focus on developing a powerful, efficient stride. Also add in longer steady state runs once per week. Most high school athletes will benefit from beginning these as intervals with one minute breaks. Pace is ~0:15-0:20/mile slower than a tempo run. Once they can run these without slowing down, bump them up to 2 miles at a time. Gradually work their way up to ~10-15% of weekly mileage in a continuous run. Now is the time to being any ancillary training as well - plyos, weights, new core routines, etc. End the month with a week of unstructured training, but maintaining volume. Do strides of varying length and pace after the aerobic & long runs - one day do 300s at 1600 pace, another day do 200s at 800 pace, and another day to 100s at 400 pace. The rest should be unrestricted. These should be about efficiency at race speeds and shouldn't feel like a workout - there should be a sense of play while doing these.
January - Continue with the hills (reps @5-7% grade for 0:45 - 1:30) once per week. Intensity on the hills is equivalent to 800-1600 race, but the pace will work out to roughly 5k race pace. Encourage them to be aware of their cycle time (start --> start) and encourage them to reduce it from week to week. Convert the steady state runs to tempo runs. For newbies who have trouble with slowing down as the run goes on, continue using an interrupted format (cruise intervals) until they master the idea of running under control. Keep the volume near, but under, 10% of weekly mileage. Continue with the strides as weather permits - consider finding a downhill stretch on a nearby residential road when the track is covered with snow. If the road is icy and the track is covered, skip the strides. Weather permitting we convert one of the stride sessions each week to what I call power hills - 8 seconds ~all-out (98%) up a 7% grade on a 3 minute cycle time. Continue with ancillary work. Race 1-2 times during the month - it should be unpressured fun and simply to help kids remember why they are training.
February - drop the hills and begin tailoring workouts to eventual event specialties. For my group that means breaking out those that will have a primary focus on the 800 outdoors and another group that will be primarily interested in the 1600/3200 races outdoors. Instead of the hills, begin doing longer intervals near race paces. Let recovery time = ~run time, but don't be militant about this. Continue tempo runs once per week, strides/ power hills, and ancillary work. Race 1-2 times during the month. Tailor the meet to the individual athlete and their goals. There are lots of meets to choose from - not every meet is great for every kid.
Note: After the mileage build up in December, weekly volume cycles: 10% below average - average - 10% above average - average
We have had our fair share of success indoors over the years with this plan, but have never bothered with the OATCCC meet as the goal is to run great in late May and June and I don't want kids even thinking about trying to peak for that meet. If we have true hot dogs, we have taken them to the Indoor National meet, but then give them two weeks after that of lower intensity work where they run with other, slower runners, as the outdoor season begins.
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Throughout all winter training, no athlete should be pushing through a cold or injury. Also, remember that weather conditions can be really brutal and that adds stress on top of the normal training stress. It's easy to over do it. If you are a coach, don't be afraid to cancel a workout if you sense the kids are getting mentally, emotionally fatigued. This is especially true for the beginners/JV-type kids that aren't always clear in their heads on why they are training. Keep the mental/emotional load at a minimum. You don't want them fried by the end of April.
I hope this is coherent even if you disagree with it. It's late. I had no intention of writing this much and have no desire to edit anything. Hopefully someone finds something useful in it.