The variety of items is immense. Most, or almost all, of the black items are weak and to throw away. Green, blue, better but little. Why get it? Mission 100% probability and 2% quality? Give it up. What's the point in getting dozens of items to throw away?
Do not see it as throwing away, see it as selling. Some extra money to buy the better items, you do want, on the market.
If you can compare and exchange the found items more easily, a stock of 20 is enough. I keep the best weapons with my guards. Only have a few in reserve and have enough space in stock with those 20 places. But for this I indeed need a diagram to quickly see if a new item is better than the old one's and where the worst old one is located. And I could be in trouble if I want to equip a guard with chosen items instead of random ones. But I'm guessing that by the time the touraments start, changing the items will be no problem anymore.