Is FIFO a good way to calculate minimum holding time for trades?

Based on the example below it becomes clear why FIFO for FX-Trades of national bankers with inside knowledge can't be effective.

With the first-in-first-out-rule (FIFO) the first purchase in a series of buy transactions is confronted with the first sale of the identical FX-pair. This method allows trades of a speculative nature to pass minimum holding duration requirements;

If a first purchase is followed by a second - say after 4 months - the insider can sell after only 2 months without having to fear any consequences as the first and last trade are 6 months apart.

FIFO is fully unsuitable in any context related to minimum holding time requirements;

An insider at a national bank can take a position in a currency pair in April, then become aware of major intervention plans in July, increase the position, then sell after only 2 months, as by that time the first position has been held for 6 months.