I ran my autos side by side as you said in veg....I then throw them in the same room as my feminized and flip them to 12/12. Nothing has gone wrong yet. I've been doing this with several strains that is have produce seeds from. Mazar, pineapple, magnum & wipe out.What I like about autos is that you can grow seedlings, veg and flower alongside each other. What you learn from one can be applied to the others (at earlier stages of growth). You don't wait for the entire crop to finish, to see how a change works.
The downside is that you have to run your lights 6 hours longer than photosensitives. More wear and tear on your lights, electric costs, cooling/extraction costs.
I didn't mean to imply they can't be run 12/12. From what I've read, the general consensus is that 12/12 yields less, and most run 18/6. Some 20/4 or 24/0. I was just giving an example of what appears to be the most common practice.throw them in the same room as my feminized and flip them to 12/12. Nothing has gone wrong yet.