I have them all gold but only as a result of my wife's encouragement. Being 40 something with a young family, GT-time is mostly from 11PM to 1AM to 3AM followed by a full time day-job

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Level 30 came racing the hard way and brought excitement and dread at the same time - I knew what was waiting for me from the forums! I also knew how hard the AMG SLS, Eiger Nordwald (Grand Tour) and some of the licenses were!!
Bronze came fairly easy on April Fools in one sitting, 2 or 3 hours, which gave me the X2010 for practice and a ranking of difficulty for the three tracks. I decided to do them Nurburgring -> Suzuka -> Monza.
I went to youTube and studied the tracks making notes and gear selections - I cannot afford to spend the time working these out.
I got stuck into Nurburgring and behold after 4 days I got a lucky gold = lots of shouting, cheers and jumping up & down waking the whole household and the dead for that matter

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Then came Suzuka which nearly broke me. After a week I was running the sector times but couldn't string them together. Eventually at 3AM one Saturday night I exploded and vowed to stop playing GT for ever

. Luckily my wife talked me back into it. She even took our 3 toddlers on a family visit and left me alone with GT5 the X2010 and Suzuka.

. Suddenly I started running incredible sector times, well within the gold standard, but the adrenalin rush was too much for a clean second lap.. . . . so close yet so far. Time-out to cool down and take a relaxing refreshment

Then suddenly I was on Vettel's tail after Lap 1 at 1:05.5(something) and the adrenaline poured into my system again. The S's, Degner and the Hairpin came and went without incident and I am closer. Try to relax a bit and focus on spoon not on Vettel right in front of me = CHECK! I am not the best through Casino but this time it stuck and the finish line came just behind Vettel. PAUSE, why is taking so long to load the next screen. . . . . and there it was GOLD at 2:09.996. No jumping or shouting, just unbelief followed by relief followed by exhaustion. It was over and I survived 10 days of driving hell by night and walking like a Zombie by day.
After all of that, Monza came in 2 hours.
Was it worth it - ABSOLUTELY!!! Now I just need to re-learn how to drive again.
For the Vettel challenge I used a DFGT wheel with no FFB, Manual, ABS = 10, SRF ON.
Good luck to those still fighting and well done to those who have conquered.
At least there is still a standard that cannot be cheated in GT5!