Kalliste,
I was never a non-believer, just a 'when?!?!' guy, but I too had struggled. It took me several months to shoot my first sub-30 9 hole round, before I finally dropped a 29 on the front side of SA. But for 18, my best had been 62 twice at BPB. During the run up to the RSG Open, I shot a 62 several times in the qualifier, but still could never break through. I topped my best 9 during these rounds, shooting 28 on the front 9 once but falling apart on the back, and threw in a couple of 29 front 9s. Finally, the last week of qualifying, after a ho-hum 31 on the front that almost induced a restart, I decided to finish out the round and shot an 'OMG' 27 on the back that really should have been a 26. So there it was, a 58. Sadly, the cut had dropped to 57, but that round showed me what was possible. Since then I have shot 60 at Congressional and 60 at SA, but haven't gone below 60 again... yet.
This week, I am upgrading my Irons and Wood. A couple more weeks, my Driver. Then we'll see... I imagine in the time after I get used to the new clubs but before I move to Legend, some very low scores could be possible.
Edit: And it's all about the putting. A month ago, 1'-5' was almost certain, 5'-10' was iffy, 10'-15' was a total crap shoot, 15'-20' was unlikely, and outside 20' was pure luck if it dropped. Thirty days later, 1'-5' is automatic, 5'-10' is most likely, 10'-15' a good possibility, 15'-20' even money, and even above 20' I feel comfortable. I am certain, both from made putts and missing closer, I have shaved 2-3 strokes off my game.