The problem for the applicant is that there is no sure way of knowing (unless you know someone on the panel) how many people the recruiter has to screen and if after 50, 100, 200 CV’s he comes across an 8 page CV, I highly doubt he’ll read past the first pages.
3 pages MAX, Covering letter with all other relevant info (no more than one side of A4) is more than enough to get an interview. The interview is where you can elaborate on your acheivements highlighted in you CV hence the CV is just to whet their appetite.