"[The] new system watches the amount of time that players are playing TF2, and gives them a chance to find items at regular intervals," writes Valve's Erik Johnson. "They aren't guaranteed to get the item at those points, but they have a pretty good chance." nope "When we were tuning this system we first looked at the average amount of time that players spend playing TF2 daily," he continues. "From there, we set the goal of most players having around 20 items in their inventory after a couple of weeks of play. If you're someone who plays a lot of TF2, you're going to get items a lot faster than that.
Johnson also touched on some of the bugs that users noticed last night while trying out the new system.
"In the first few hours after the release yesterday, we had some issues that prevented the system from working properly, so that timeframe was not indicative of the system as it's designed."
Johnson further noted that players finding duplicate items is an intentional result of the system, as Valve plans to add the ability to trade the items in a future update.
"Giving players a method to influence the system so they can work directly toward getting specific items" and "adding more rare items like the hats" are also goals that the team revealed.