Hi there!
Have you done any background reading here yet?
Welcome to the DMT-Nexus
forum.dmt-nexus.me
Welcome to the DMT-Nexus
forum.dmt-nexus.me
wiki.dmt-nexus.me
Optimisation could mean a lot of different things depending on your exact situation. You seem to be focussed on yields, but how were you assessing extraction efficiency for your particular bark? The methods that you mention should be quite capable of delivering a high yield of whatever the content of the bark was, particularly through following the principles of extraction and not just some instructions.
There's every chance that you had weak bark, from what you're reporting, but just to be sure, it would be helpful to have an account of your extraction practices, ideally down to the minutest details, in order to stand a better chance of troubleshooting your particular situation. Having all the toys may not add up to much unless they're used in a competent fashion.
Times, temperatures, materials, actions - all of these are relevant. But for your question, understanding is probably the most important factor.