Trying to work on too many projects in one day can be bad. There's a line I always think about (I forget where I read it): "Context switching is expensive." Expensive in terms of energy burned trying to get back "in gear" after switching contexts. Comics work involves many levels of nested problems and projects and it gives the brain a good workout to keep track of all the levels of tasks and problems. So don't make it worse by switching out whole projects/contexts too often or you'll get mentally tired quickly, and begin to feel exhausted and cranky.
If you are feeling anxious, you should sit down and ask yourself why. If the answer is "I don't know what I should be doing right now," maybe you should think about having a daily routine. Then the answer to the question is simple: you should do whatever comes next in the routine. Do whatever comes next, and don't let your anxious mind fool you into coming up with new things to worry about to distract you from your routine. You might start to think "No, the real problem is I don't know what I should be doing with my life!" This is probably not true. You probably do know. Go back to the routine and laugh at yourself. But if you really don't know what you should do with your life, you should sit down right now and figure that out.