So we all know that TL says they don't tinker with the drop rates:
So here is my theory. Somehow the drop rates are connected to how many of an item you have in stock.
So let's say that the level is set at 20. If you go under that level you will get lower drop rates and if you go above it, your drop rates will be higher. This will cause the effect that we feel once we start using something from our inventory. As long as the level is high we feel good drops but the minute we start using the item, our levels drop below 20 and the drop rates go down.
TL doesn't have to tinker with the rates, it is built in.
I don't think they do this to make us buy stuff. Just to pace the game.
That's my theory.
Toughts?