For my workouts outdoors, I have been keeping my cadence in the “green” zone on my Xert Garmin IQ app (the Bioshift window). Lately, my moderate endurance rides have suggested I keep my cadence around 50 rpm. The green zone is pretty large (up to 60 rpm), but the sweet spot in the middle is @ 50 or even lower at times, even at FTP power output. I’m wondering if I’m interpreting this correctly. It would be great if there were a video of using the app on a Garmin device (I have a 1030) during outdoor workouts. I don’t recall every seeing one that walked through and demonstrated features and proper use.
There isn’t much detail on this and am not sure how it works. I have the impression recommendations are made based on the current ride, rather than looking back over all of your history… I find if I start out and stay around 90rpm that will be recommendation, but if I start out and maintain at a lower cadence it also recommends around that… probably one for the Xert guys to give a view on!
CO is applying some algorithm based on your individual performance and torque metrics.
CO’s history is Bioshift: Xert and Bioshift – A History – Xert
I think fast twitch/slow twitch composition and your physical build are contributing factors.
Some cyclists are natural spinners. Others are not.
IME CO has lowered my inclination to spin fast for no good reason. 
From what I can tell this corresponds to a lower HR for a sustained power output. More efficient?
On the other hand there is no way I can sit in on an A/B group ride for long without high rpm.
Thanks for the feedback. The other day I was training with the Xert Workout “Smart - Working Man” and my average cadence, following the green zone of the cadence window on Xert Player on my Garmin 1030, was an average of 48 RPM for the entire workout. I was following the workout and assumed this was just low cadence training, but I wanted to be sure. Some workouts the cadence window suggests 70s, 80s and above. Indoors, it’s very easy to follow the suggested cadences, I just don’t remember anything that low indoors. Hopefully, one of the Xert experts will weigh in. Maybe I’ll hit up the FB page.
If you mean middle of the green zone didn’t vary between recovery and work intervals something is wrong.
In Garmin Express under Connect IQ apps there is an option to reset CO. I assume that means start over and relearn your cadence patterns.
Perhaps you should reset and start pedaling faster 
unless you really feel comfortable at a lower cadence.
In either case recommended cadence should vary between effort and recovery intervals.
It may not change much depending on the type of workout but it shouldn’t be the same number.
If it is not changing I suggest you file a support request with: support@xertonline.com