Wendy:
I would asume it's too early to say. Personally I am not out there doing an IS video every day, maybe some are. I like to intersperse new videos with old to make interesing combinations, vary the intensity days, and just keep it interesting. It's only been a couple of weeks since the videos arrived.
Even if someone were to be doing nothing but vids from the new I-series daily, our bodies change throughout the month in terms of available strength and stamina, that I would think it would require a few monthly cycles to really be able to make this decision.
That's my opinion at least. No doubt, someone will come in and disagree with me in about two seconds!!! That seems to be the nature of these forums...
Cheers,
Clare