I had a similar experience to the OP on the CRJ. My sim partner didn’t make it through systems and I struggled. Call outs are hard to practice on your own and others were busy practicing with their sim partners. I observed others sim sessions that were much smoother than mine. I had a different instructor every day so poor continuity. Had the late sim session 8pm to 2 am which was tiring since noise in the hotel started at 6 am and sleep was difficult. Not having a sim partner meant not watching someone else go through the maneuvers to learn from their mistakes. Ended up using up my extra sim sessions and made dumb mistakes in the Manevers Validation so was told by the examiner I should be good with a training session then retest. I got a call from the training manager and he said I used up my sessions so it was the end of the line. Was told I should come back in 6 mos because I was really close and was the kind of person they wanted at SW. Most of my instructors were great, one was terrible and I had the examiner that was the gossip at the water cooler as the toughest. I’m not one to make excuses and I studied my butt off but couldn’t pull it off. Undecided if I will return at SW.