What is the basic rule on how many times you can do the same thread. or you can submit as many as times as you wish as long as the deadline is not yet over?

You can work on only one thread at a time. Once you submit your work and it is pending approval, you are free to work on another thread within that job or work on another job entirely.

Once you complete a thread the employer will be notified and will have three options: Approve, Reject or Return for Revision. If the thread is approved, you're finished and payment is automatically deposited into your JobSpooler account. You won't need to take it again, but you can take an additional thread from that job if the job manager didn't limit that number. Job Managers can limit the number of threads a single user can take from a particular job.

If the thread is rejected, it will be returned to the pool, and you will be free to take another thread (unless the job manager decided to block you from taking any more).

If the thread is returned for revision, you will be requested to make changes and resubmit the thread.

Once you have submitted the thread, you cannot make changes until the job manager takes action on it and returns it to you. If the submission is rejected, that was your only chance.