This is an idea. I might try three week blocks. I always feel awful in the last week, but maybe that’s me hitting supercompensation. I’ll live with mild cold symptoms if it means I’ll get faster.
I’ve also started tracking my sleep. Last night I got a whopping 7 hours, and I think I’ll make that my new target. Baby steps.
I can’t claim it was my idea. I think Purple Patch coaching have some plans as 2 weeks on and one week off as by the time the 3rd week hits or most likely the last 4 days you can be very tired and feeling abit toast.
Maybe that suits harder training as you certainly seem to be nailing it during the build phase of the cycle. Hope that will help, if you still get sick then not sure 
.
Also I remember a TR podcast where they mentioned an extra hour a day sleep can equal an extra whole day of sleep over a week
Just came across this article today which talks about people having different circadian rhythms and therefore not all needing the same amount of sleep due to genetics. Worth a read if you’re interested.
Are you on a training plan with your 10+ hours? I was sick a lot last winter and blame it on to much intensity… this year was great following the medium Plan. So if you are following a plan AND adding intense rides this might make you sick. Zwift racing on top also does tend to have this effect.
Definitely agree. I can then shorten this to 4-6 hrs per night x 2 towards end of the week and then have a couple bigger sleeps on weekends to balance it out