Also, can someone explain why I have not seen 3*item drops after 400,000 (and counting) consecutive attempts? Possibly too low level to win all items?
Level doesn't factor into Item Drops. In fact, item drops are not considered until after the battle is over. Once the battle ends it loops through each defeated enemy and totals the exp, ap, and gil won from each enemy and items are dropped in the process. They're calculated like stealing items, but without initial level considerations.
Basically, if (random number AND 63) <= [drop chance] then the item will drop. The random number is determined completely by the RNGLUT in the KERNEL.BIN. The set is never incremented so it just cruises in a straight line down the numbers checking if they meet the criteria for dropping an item. Take a look at the RNGLUT in WM. I just copied that whole thing and did a MOD 64 on each entry in Excel. It looks like there isn't a place that will let you get six items from six different enemies unless those enemies have a high drop chance. It doesn't look like it's possible to get more than three from a Battery Cap x6 battle.
In order to be able to win six items from six enemies, the drop chances needs to be pretty high for an item.
Drop rate: RNGLUT pointer:
27+ 31, 32, 33, 120
26+ 32, 33, 120
25+ 120
As you can see, there has to be freakishly high rates of dropping for this to occur. A drop rate of 8 is typical for "common" items. Some go as high as 32, but that's Vlakorados and King Behemoth which are singular enemies.
Since most drop rates are 8, then it's impossible to win more than three from any number of enemies in a given battle. There's a 10/256 chance that that will occur.