I am in a bit of a dilemma. I have to make a 3 layer cake but I have an apartment sized oven and will only fit 2 cake pans at a time. Do you think it would be ok to bake the 2 layers and then the 1 remaining layer immediately after. The cake usually bakes for about 30-35 minutes. Would the batter be okay left out while the other two layers bake. Thank you.

I have done this before because I have a limited number of pans in each size. I has worked just fine for me. Good luck!

I do that all the time, no issues.
I also freeze left over cake batter in large ziplocks. Then when I need it, I cut a hole in the corner and squeeze it into the pan.

Yep it will be fine.

The batter will be fine left out. However, if it gets really hot in your kitchen, you may want to put the batter in the frig. Either way, just give it a stir and it will be fine.