I'll be interested to hear how it goes.
I don't think it really matters if you do other imagestreaming while you're doing the 30 day challenge. "You get more of what you reinforce".
Having done the 30 days, I got much better at the process of letting the stream run and describing it. I remained dissatisfied with the "answers", many of which remained impenetrably metaphoric.
So, one day, I thought I'd do a little experiment. I came up with ten questions on a particular topic. The questions tended to be more specific than my previous htt ones. Some of them were "yes" or "no" questions, which seemed inane but I threw them into the hat anyway. Then I did 5 htts in a row, choosing from those 10 questions. This took about an hour. At the end of it, I had a lot more clarity on the topic, and much clearer, more immediate imagestreams. And, the metahors became more accessible.
Interestingly, none of the "yes" or "no" questions were among those picked.
--Brian