Well, the hardware came "free" (once it was built for the EOS experiment), so it is up to the software to worry about doing a more difficult job.
Each "plane" is the thickness of a pad, which is 1.2 cm for the EOS TPC. The planes are built of 2d pixels of size 0.55 cm x 0.8 cm, or 2.27 pixel/cm^2. This size is based on the intrinsic "size" of the hit, and how it grows with diffusion.
The design of the 2d hitfinder in E895 is such that a hit starts with a "significant peak," and a peak's significance is based on a peak-valley cut. Thus, there must be a valley in the 2d pixel space between two hits-- the closest hit cannot be "on" the next pad or time bucket. (Of course, hits are not "on" pads or buckets; see the other 2dh pages or Stony Brook pages for details.) This means that the maximum hit density is 1 hit/((4 x 0.55 cm) x (4 x 0.8 cm)) = 0.14 hits/cm^2. Keep in mind that even this modest density is achieved only in the theoretical limit where the tracks conspire to arrange themselves perfectly. For the first few padrows in particular, this value is strongly exceeded in the zero-degree cone.
To decide, look at these pictures. They show contour plots of the track density and hit density overlaid, with contour lines in different color. You cannot tell which is the track density and which is the hit, but you can see that the two start to differ at track densities around or a little higher than 0.05 tracks/cm**2 (which is the green contour). E.g. although the track density hits 0.1 (blue lines), the hit density never gets that high (see also the "tour" above).