It would be my opinion that you could follow a nine-day cycle with 1 SOS (something of substance), 2 easy, 1 SOS, 2 easy, 1 SOS, 2 easy, etc... without issue for competing in Dopey. For my personal training, I do: 1 SOS, 2 easy, 1 SOS, 1 easy, 1 SOS, off, repeat every week cycle (used Hansons) and haven't had any issues (and that includes going for PR effort on all 4 races). The goal though would be to make the training more difficult than the actual race not by pace but by cumulative mileage and time on feet. If someone were to attempt a maximized 9-day cycle I would suggest something like:
Day 1 - Track 90 min (actual track work <50% of workout)
Day 2 - Easy 90 min
Day 3 - Easy 90 min
Day 4 - Tempo 90 min (actual tempo work <80% of workout)
Day 5 - Easy 90 min
Day 6 - Easy 90 min
Day 7 - Long Run 120 min
Day 8 - Easy 90 min
Day 9 - Easy 90 min
This way your simulated Dopey of 5K, 10K, Half, and Full is actually within the days 4 through 7, but you're likely running longer/further during days 4/5 then the real Dopey almost every week building to Day 6 and 7. Towards the end of the cycle, I'd probably bump the tempo past 90 min, the Day 6 past 90 min, and the Long Run maxed at 150 min. I'm a big believer that endurance running comes down to a two key timeframes. Training between 60-90 minutes to continue the fatigue from previous workouts but not too much to take you past the breaking point, and the second timeframe of a max of 150 minutes because recovery takes too long beyond workouts that long.
I saw a recent research article (and I can't find it at the moment) which had subjects in two groups: traditional rigid plan (3 SOS per week with easy on other days) or a plan based on HRV (heart rate variability). The subjects in the heart rate variability group determined whether they were to do a SOS or easy based on a heart reading measurement in the morning that measured the time between heart beats. Normal timing equaled SOS workout, but a shortened timing meant an easy day. The group based on physiological signs and symptoms (HRV) improved better over the course of the training cycle (and actually did less SOS I believe but I'm not sure on this point). Same concept as a nine-day plan but a different approach. Regardless, a nine day cycle could definitely work for Dopey even though Dopey is potentially 4 SOS in a row in my opinion.