If your saying, just leave them ON=Powered Up a 100% of the time= forever?
i've always thought of heat as electronics main enemy.
so no, i wouldn't leave monitors on all the time.
your asking alot from your heat sinks to dissipate the heat that long. HSinks which are a fixed mass, so eventually something would give. one transistor leg, one capacitor, maybe that voltage regulator dioide? chips tend to get very hot...hence the little fan on your Pentium and Celeron, since ~1991-92...
if it wasn't for that little fan there wouldn't of been a Pentium.
You ever touched a computer chip after its been ON and working for awhile? they can burn the F out of your finger!
If your asking about applying the power to the Monitors (and amps)..
Off first and On last to avoid the common popping sound. Volume at zero.
If your talking about using the power strip to reduce wearing out the Monitors On/Off switch on the speakers themselves...
its a good practice for long term reduction in wearing out the switch which is mechanical. most switches can often take >100,000 of toggles though...but if you can avoid it why not? a power strip is cheaper than a monitor switch...especially for live gigs where you can change out a power strip easier than ordering a special on/off switch.
same with these new plastic guitar plugs or mic jacks...plastic man..plastic monkey stuff.