I think that it depends on the strain that you are growing. My AxT run was done in a Phototron, (remember those?), and I got 3.5 oz. off of a 1.5' plant. I also ran a Durga-Mata cross in a tent under exclusively HPS light with a light cycle of 18/6 throughout the entire grow and that plant turned out to be a beast. I think we got closer to 4 oz off of that plant. Within that same run, I had a AK47 cross and a Hiesenberg and they both had a estimated haul of 3 oz., and all of those were autos. So, my belief is that it is directly relative to the auto strain that you are growing. Just as a suggestion, take a look at this one:
https://www.cannabis-seeds-store.co.uk/auto-flowering-seeds/dutch-passion/autoultimate-feminised-seeds/prod_6066.html. From what I have read, it's like the breeder dares you to try to mess up this plant when it grows; you can't! Some of the descriptions that I have read about this is that it has a ridiculous yield, grows under pretty much any and all conditions and really doesn't care if you feed it or not. I have never run one of these, just going off of what I have read.
I agree that the Skywalkers seem to be kinda small but that is probably characteristic of the strain not because it is an auto. You may consider crossing it with something else to make it grow bigger and thus give you a better, bigger yield. In fact, since this project has started I have been on the hunt for Chem #4 auto seeds to cross with one of these Skywalkers. Only because I know for a fact that if I am successful at crossing one with the other that I will have Dogwalker autos and that was one my best all-time favorite smokes. I'm not sure about size or yield, but the buzz was simply incredible; nothing like it.
Anyway, sorry for the long response and don't misunderstand me, I am not trying to pick a fight, just trying to offer my advice for what it is worth.
Good luck with your grow and I hope everything turns out better than you expected.