Over a year since this post but I wanted to add to if for two reasons. Firstly, it helped me enormously when my trusty Colormunki Photo calibrator started giving awful profiles yesterday.
Secondly, to be clear, yes Calibrite or whatever they are called this week, are rubbish. However, thanks to the LL forum, I downloaded the latest software and my new profile for my laptop is fabulous.
Thanks to all, Andrew, agree totally about the ambient light thing, pointless...1
Steve