I was always sort of sad and jealous seeing users with so high LPMs. I did almost all, worked out many options alone or all at once but it was all in vain. My all efforts to increase LPM mostly resulted in vain. There were times in between when I got LPM of like 45 or so, but that too stalled after some SER updates, reason being unknown.
I got desperate to the point, that 6-7 days back, I started working like a mad scientist. Day and night, I spent my time in tweaking SER (with only around 13 projects active, 7 ran each for 20 minutes with the help of scheduler), trying various options, some with one or the other and so on. By hook or crook, I wanted now really to achieve good LPM.
So as a result of these past days, I finally am now able to push to 55-60 LPM at constant rate (as of today's observation).
So work hard to the point until you achieve your desired rate. Its tricky, I agree, but you gotta figure out. What my advise would be, might not work for you. For example, my friend just followed simple options out of scratch SER with no global site lists too and he keeps 90 - 100 LPM. So that all depends really on...really not sure what, but its different from version-to-version and system-to-system. So just work and tweak out until you achieve the desired output.
The new versions might change my performance too, not sure, but I'd now never give up. I'll keep this thread updated if needed.
edit: Also just in case anyone wonders, I now also keep the JUNK tiers (i.e. T1A, T2A, T3A, etc) to never verify, but would just verify all of them at once in the weekend so I can increase the number of submissions.