In other countries there are also similar agreements between network operator and industry. There can be years between situations in which such agreements are activated.
In the UK, is such agreements activated multiple times a year ?
In a well managed network, there are a number of fast starting gas turbines with total capacity larger than the largest single (nuclear) power plant. If the largest unit fails, these gas turbines are started within minutes.
However, if all emergency gas turbines are running as a result of a single big failure, the network doesn't tolerate an other big failure.Either the output power of existing power plants must be increased (or started) or some big lads has to be removed within an hour, so that the emergency gas turbines can be stoppled and be ready for the next big failure.
These emergency gas turbines are expensive to run with natural gas and their efficiency is low, so you do not want to run for a long time.
For these two reasons these emergency gas turbines are used for les than a few hundred hours each year.
Even if most energy in the network is produced with unreliable renewables, some emergency gas turbines should still be available. The question is how these are going to be fueled e.g. with bio methane or natural gas even if the climate alarmists think it is a bad idea to use NG.