I'm sure Robin will answer this himself as soon as he's next online, but as a user of the CBT4Panic programme I don't think it's inappropriate for me to suggest that the answer (in my opinion) is: it depends how much work you're prepared to put in. If you gloss over the workbooks (not suggesting you would) and/or put it into practice only one day a week, or more occasionally, your progress is likely to be slower than someone who really takes time & effort to absorb the workbooks, really owns their recovery, and practices what they have learned every day.
I'm in the middle. With Robin's guidance I've been tackling my practical learning in a slightly different way - one that works for my life - rather than following the workbooks verbatim. After 3-4 weeks of this I'm feeling much better, more positive, and more equipped to carry on being in control of my recovery.