I was at a WM Money Center recently loading my BB. A guy walked up with 20 cards (I am not sure what they were -- I was a Visa logo). He wanted to put money on all of them.
The CSR said.... aw, maybe you can do 2 or 3 at a time...I think it is illegal to do that many at once.
Then a manager came over and questioned why he wanted so many. The customer was agitated and said it was not of their business. "It's my money. It's my accounts..."
I left the area before seeing how it played out.
I've been asked a few times why I load in $500 increments instead of a full $1,000. I just tell them I keep my accounts separte.
Although I have not been questioned when purchasing a large amount of GC, if I was I would say they are employee bonuses.