If games end so quickly then why do we have 6 item slots instead of 3 or 4

doesnt always end that quickly.

you see, I have an extremely opposite perspective in which i think that If the game drags on long enough we should be able to combine certain items that way we could keep scaling past 30 minutes

not everything

but maybe like... IE and BT which are often together, add 1k gold and you now have Infinity thirster, with the combined stats of all but then you have another item slot.. maybe for a black cleaver?