As a PhD student at the GC, I rely on teaching within CUNY every semester for extra income, but mainly as the only job through which I get health insurance. I never know from semester to semester whether I will get a course or whether the course I am scheduled to teach will run. Frankly, it's so anxiety-producing that I am trying to get a second course at the other university I teach at (in the NJ public system) and buying health insurance through the NYS health exchange next semester.
If other student adjuncts make the same choice I'm considering, one possible consequence is that CUNY still has to pay for student adjunct health insurance, but colleges wind up with new student adjuncts every semester. Based on my experience, teaching the same course a few times has made me much, much, much more effective as an instructor.
Another choice some of my fellow students have made is to accept to teach a guaranteed course within CUNY, even though it is a course they have never taught and that is not really in their area of expertise, just to be sure to have a course in order to get health insurance.
This issue seems to me to be detrimental to the quality of the education offered to undergraduate students in CUNY colleges.
As far as relationships with chairs, well I never say no.... As a consequence, I'm teaching in the middle of the day three times a week for one hour, with a commute of 1h15min each way. This huge time-suck is definitely prolonging the time-to-completion of my own degree. If this is at the forefront of my mind when I arrive, I am not as patient or focused as I might otherwise be during class.
The alternative plan I am considering is, as mentioned above, teaching in another system that offers a little more predictability, and taking student loans to reduce my workload.
I have consistently received average or above average student evaluations and glowing classroom observations. To the extent that CUNY relies on itinerant labor for instruction in undergraduate programs, it seems desirable to retain effective instructors rather than put them in a position where their best option is to do anything but teach in CUNY.