Actually it works , rather then add new frames for a clip into your time line make a short one just as you said the first ones are working well . To prolong the sequence save your first frames ... save the last pose and cam position then start the next little sequence . so even if your sequence on one cam view is 30 sec splitt it off into smaller Portions . when gathered all parts for your 30 sec put them together but keep in mind to just keep the actual cam view . these steps will also help you to find corrections you need to make on the parts . so name each Part with the frame numbers to find it easy same with the cam and last figure pose. Work with different cameras this can shorten the work of your clip to make it longer with the same action from another perspective.... from a different angle you would think it is another sequence.

Think a little the way they were making animations on Paper then you will find a good way to make it with Poser

also Note : do not move the light to much else it will look like the sun is turning around your Actor this can be very disturbing so keep a good eye on shadow and Light