Maybe small amounts withdraw faster. I remember cryptsy where small amounts could be withdrawn within a day where large amounts could take weeks/months.
LOL yea all this talk of Polo not withdrawing BTCD does remind me of Cryptsy. At Cryptsy, I remember that larger withdraws wouldn't go through at all or for some random reason I would get half of what I wanted. It was almost like they were staking with the very BTCD wallet that hinged upon their customer's withdrawals/deposits for their exchange service. Still not home yet just taking a break. I don't have the BTC to spend on more BTCD today. How much were you withdrawing just curious? Usually, Polo is pretty transparent about this stuff.
Update: I checked my wallet and found that the withdrawal went through

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I don't use polo. I only used it to buy doge a year ago.