I'll add that my spring series was designed for doubling up.
5s did the 5s.
4s did 4s (to do well) then the 3-4s (to train). If a Master or a Woman they could do those instead/also.
Women did Women (to do well) then whatever Category or Masters (training).
M45s did Masters (to do well) and their Category.
3s did 3-4s and P123s.
Only shortchanged group was the P12s who weren't M45. To try to accommodate that I made the races pretty long, 40 miles or so. I think that was a mistake, it dissuaded 3s from lining up and the P12s went and did a few hours on their own before/after the race. If I could do it again I'd make the P123 race 30-35 miles. I'd shorten the 3-4 race to 25 miles, not do 30 miles.
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"...during the Lance years, being fit became the No. 1 thing. Totally the only thing. It’s a big part of what we do, but fitness is not the only thing. There’s skills, there’s tactics … there’s all kinds of stuff..." Tim Johnson