It all depends on your soil.
When I lived in Birmingham AL, some of the worst soil in the country, not much will get deeper than 3-4 inches in the worst of that soil.
Most of the time 3" would be my limit.
Not my F2, my Compadre, my Vaquero or even a friends E-Trac were able to penetrate that highly mineralized soil mixed in with the veins of natural iron ore that runs through the entire area.
There are a few spots with better soil in the area and once I was in some decent soil that was moist after a rain and got a solid dime signal that said 7" on my screen and this dime was every bit of that 7" deep...maybe a little more.
Switching to my better soil when I relocated to Kansas, everything I own is going deeper including the F2.
5-6-7" on coin size objects and trash is now the norm, not the exception, large junk like cans way deeper.
I have read many, many posts from owners of the F2 and there seems to be a huge range of results from some that say they get no further than 4" with the standard 8" coil to others that say they get past 8".
Most that have the 10" coil do find that about 2" more in depth is common...especially in moist soil over that 8" coil.