You should slowly increase value of sales incrementally (regardless of whether you got an allowance increase or not, as that doesn't mitigate the risk of suspension).
And you should remember there is no such thing as an immune account and regardless of all your precautions you could get a suspension when dealing in high risk items - its just the nature of the beast unfortunately. All you can do is improve your odds.
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AGED SUPER HIGH LIMIT ACCOUNTS: 10,000/$1,000,000 and 25,000/$500,000
i have about 12 fb and i've sold about 30 items, my hold was gone, then all of a sudden i started getting 21 day holds again.
You have to understand that there might be various trip flags on PP side that caused holds to come back - it could even be related to the BUYERS and potential risky payments e.g. echeque or weird cc source, etc