Well some flavors like cinnamon don't really come out, but otherwise it's kind of as needed. I keep spares of all my gear and swap out weekly to clean the set I am using. Also a good idea to keep spare o-rings, tank glass, etc if you can. Nothing sucks more than your vape not working with no backup.
If cinnamon is anything like menthol, it will come out using dawn.
I once got a used Kayfun that had nothing but menthol used in it. It was horrible. First I took out all the o rings and soaked all the parts in PGA, then I boiled it, then soaked it again in PGA, boiled it again, and allowed it to dry completely.. still smelled strongly like menthol, so I went online to find out how to remove menthol from a tank and someone had suggested soaking in straight dawn dish soap, so I tried that. I soaked overnight in dawn, rinsed well and did another boil, and lo and behold the menthol smell was gone.
At that point I put in all new o rings, new glass (as both those components are more porous and harder to remove the menthol from) and put the Kayfun back together..
It was like new, as if it had never been vaped in before. The same person I got the first Kayfun from, sent me his clone as well since I liked the Kayfun so well (very nice person) and that one had, had nothing but menthol vaped in it as well. So instead of starting that time with PGA, I started with dawn, I first washed normally, then soaked in straight dawn, then did a boil and a second dawn soak, followed by an other boil..
That time I didn't change out the glass, but I did change out the o rings and again, good as new.
So I assume the same would work on cinnamon, because it's as strong as menthol is.