Most cities provide pressures between 40-60 psi... not 250.
Even if they did, you would still find that the volume flow rate (gpm) of a 3/4" line is going to be approx. 7 gpm. So 7 gallons per minute, is 7 gallons per minute... no matter how high the pressure may be. That is assuming a water velocity of 5 ft/s. Higher velocities will give you more flow, but not by very much. They don't do this though, because of the potential for noise and damage. You would increase the pipe size instead.
Also, no matter what your water pressure is... just remember that you will be losing about 8 psi for every 100' of pipe (on perfectly flat ground). So if you do actually only have around 60psi, you may find that it doesn't quite spray as far once it has traveled 400' through your garden hose.
Man I pondered being a dick for hours about that 250 psi street pressure. Thanks for beating me to it.
You can get higher main pressures, but you really only see it at night with low usage. Highest I've seen is 125 psi spikes at night. Then you get to go door to door selling pressure reducing valves
Also don't forget your water heater relief valve is set at 125psi
Lite the sky and own the night.
I'm a first time dad. Our baby girl was born on Dec 30, 2010.