It is possible that 30mgs is not enough for you. Everybody is different. If you have a fast burn rate....you may be burning through the Adderall in 6 hours and that is why you are taking the extra dose. I have got to go back and read some of your earlier posts, but it sounds like you have not yet hit the right dosage for you. Its is trial and error. And something you need to talk to your psyc about. If you are feeling fine till mid afternoon, then the panic attacks etc. start, then this would be a sign that your dose is not enough.
I have got more info on this that I will send to you. Gotta run off to a doctors appointment , but will get back to you.