i CAN HAS explanation
The problem is that some systems require more back (or directed) pressure than others to function properly... ie 7.5 inch vs 20 INCH
Its not a problem of giving it too much pressure, its a problem of giving ti enough to be reliable and in this case avoiding cycling issues...
Pressure is just a measure of force per section area - it is the amount of energy transfers that matter - ie volumetric flow.
If a system is calibrated with a certain volumetric flow (fixed gas port size with a specific port pressure - time of pressurization is fixed by the distance between gas port and muzzle), increasing the pressurization period means increasing the total volumetric flow and dumping excessive energy in the system.
Unless any of the 3 variables is wrong in the first place (gas port size, distance between muzzle and gas port and the pressure produced by the ammunition), increasing the pressurization period does nothing, nor does increasing the pressure.
In fact, if the device does increase the port pressure, it will lead to hyper extraction because it will be increasing the volumetric flow rate and duming energy into the system faster than it is originally designed to.
I hope I still remember enough of my fluid mechanics to get this right!