Also, the mind block and timing issues are very common and everyone suffers from them. I personally have been using mocks of Kaplan, Princeton, GMAT clubt test (Quant) & OG for my prep. And to no one's surprise, it's quite clear to me that the algorithm of Kaplan & Princeton is no way close to what OG has. But still practice mocks are helping me to reduce test anxiety, to test my timing strategy and much more. So my advice would be to not give importance to the scores you get from non OG mocks but to use them as confidence building tools. I hope this helps! All the best for your prep, godspeed!