After fantastic advice here I've taken up and am working through my eCPPT certification. Overall I'm finding it not to bad, but I'm noticing a lot of overlap with self taught knowledge I obtained through reading a ton of books on security related topics (I.e. Web Application Hackers Handbook, etc).
Digging deeper into many of the syllabuses of further certificates, I'm noticing a lot of the material seems common throughout. Information gathering techniques, enumeration, vulnerability assessment, exploitation, post-exploit and maintaining access etc. Now obviously this is always going to happen to a point - these are central tenants of pen testing! My question is though how much value do you see in doing a range of certificates? Does this change if we're talking the same organisation vs different organisations?
I.e. What percentage of knowledge overlap would there be between OCSP and OSCE? Would someone who has completed OSCP & OSCE get value out of obtaining GPEN? Is every course going to talk about the variant of nmap scans or do they start getting more specialized rather than 'from the ground up?' and hence rehashing a lot of the fundamentals.
These answers help me figure out the value of pursuing multiple certificates. If a certificate is $1000+ but I gain a heap of new knowledge then I think it's fantastic value. If it costs $1000+ and I relearn 90% of the knowledge from other courses, but only 10% new then it's value relatively goes down. I also must note that I'm not meaning to be critical in any way of eCPPT when I'm asking these questions, it seems to be a good course. As I'm fortunate enough to be doing this out of interest (at this stage) rather than for career purposes I can be a bit more choosy with the qualifications I pursue.