"thermo-style" command allows us to print the average pressure of last
N screent output.
Do you know how to print average values of pressure (or pxx,pyy,pzz,
etc.) over every given timesteps? For example, the average pressure of
1-100 steps, 101-200 steps,..., and so on.
Nope - LAMMPS doesn't currently have an option to do averaging
every step. Unless you turn on thermo output every step and
use the output option you mention.
This is b/c the eng/press require extra stuff to be computed by
the potentials. That computation is not turned on unless its
a thermo step.