I try to always keep the oil level in my '08 above the crosshatched marking on the dipstick but preferably not ever much above the top of the upper hole. According to the guidance (this being for whatever constitutes "normal street duty" in Ford's eyes) in the owner manual, that probably constitutes "over-filling". But I have a very specific reason.
Hard cornering means that oil tends to collect in the cam/valve cover that's on the outboard side, because cornering g's work in opposition to gravity and slow the rate of oil drainback from that side. This effect is at its worst in common V-type engines in the 90° arrangement, where at 1g cornering there is nothing left from gravity causing oil drainback. Actually, the no-flow condition happens a little before 1g due to chassis roll in the corner, somewhere in the 0.9x range below 0.95.
At 0.6g cornering - a stupid easy level to reach even in street driving - the net force causing the oil in the outboard cam cover to drain is only about 35% of what it is when you're driving straight ahead. At double that, which I have datalogs to support being possible even on true street tires, oil that's already in the outboard drain passages wants to climb back up into the outboard cam cover . . .
Yes, the inboard cam cover will drain a little faster, but since it can't drain any faster than the oil supply into it is being replenished it can only provide brief "help".
Basically, a slight "overfill" provides a little cushion against uncovering the pickup in any hard cornering environment. It's a fairly common technique among those who autocross or do track days in a car with stock or stockish oiling systems before going to something like an Accusump or a full-on dry sump arrangement.
Norm