Parametric EQ vs multiple bandpass filters
a graphic EQ need not mean cascaded shelves.  it could mean cascaded peak/cut bell filters.  maybe with shelves as bookends, maybe not.

the bell filters are symmetrical in log freq (or the pitch scale) and are naturally spaced equally in log frequency.  you can draw any reasonable shape with a sum dB of these cascaded peak/cut filters.  but nothing too wild.

you could also do this more analytically with a sum of FIRs, all time-aligned.  make a series of overlapping complementary window functions (like a Hann) but operating on log frequency instead of linear frequency.  but that frequency response can be interpolated and sampled in linear frequency and an FIR can be derived from that magnitude response with a delay of some sufficient constant value.