I can buy L$ up to my tier limit on any given day, wait 24 hours and repeat the process because that is how the system says it works. When I try to sell that same L$ purchased, I can sell up to my tier limit but the limit doesn't reset until the order is actually sold so I have to wait 24 hours again. On some sales my orders are executed 48 hours after they are placed so I get hit with 24 hours wait (normal) when the order is placed and another 24 hours when the order is filled(bug). You are able to buy the same tier every 24 hours but if the sale is executed 24 hours later you have to wait 48 hours after the sell order was placed to use the same tier again. If you have the money to buy every time your tier allows you get a huge pile of L$ waiting for your sell tier to clear its 48 hour hold.
This is the 3rd time I have asked this same question and it is yet to be answered. If LL waits long enough and I can keep raising my currency trader tier level it wont matter because my daily tier limit will exceed my ability to purchase L$ faster than I can sell it but at a $5000 daily limit it is a pain to sit on 100s of thousand L$ waiting for your sell orders to clear that were placed 48 hours previously so you can sell it.