I know this a bit older... Don't know if you found your answer yet...
But I say it depends on the individual. A 4x2x2 is what is generally recommended for a grown male. I have kept some of my males in 4x2x2s and they don't seem to really roam the enclosure as much as say a Veiled would. I moved a few of my docile full grown Panthers into 18x18x36... they are doing fine, and seem happy with their space. On the other hand I have had males that based on their activity level I would not consider keeping them in anything less than a 4x2x2.