I live in Finland and me like a large number of other Finns have a plan in which the price changes every hour according to the market price. Typical price for electricity is around 4c/kWh in the summer and around 15c/kWh in the winter. However it's not uncommon at all for the price to spike into 30c/kWh or even 70c/kWh. Last winter there was a day that it spiked to 200c/kWh.
How do we deal with it? By turning down/off the heating if possible and burning wood instead. If not then you just deal with it and have to pay significantly more for a few months. Then again if your plan has a fixed price to like 10c/kWh then that also mean you're paying that even when the price drops to zero which also is not uncommon at all. Often happens several times a week during the summer time. Sometimes it even goes into negative. It's still not literally free though since the transfer cost is around 6c/kWh plus energy fee and taxes.
How do you keep up with the current price? Does your thermostat have a setting where if the price is above X then turn off? Do you just come home to a freezing house and say "oh the electric is too expensive, guess I'll grab some wood"?
I check sahko.tk in the evenings to see if it's going to be particularly expensive the next day. This is mostly in the winter time, at summer I hardly pay any attention to it. They usually warn people in the news too for the handful of really expensive days in a year. Depending how high it gets I might turn off the heating for the peak hours but generally not because it doesn't really make that of a big difference as the prices average out over a long period of time. Some people have automatic thermostats that turn off the heating after the electricity price passes a certain limit. My water heater for example is set to go on during the night when electricity is at its cheapest.
Are the predicted prices ever crazy far off from what they actually end up being like what happened in Texas last winter? Where am outage causes price to go from like 20c/khw to 2000c/khw over a one hour period?
No.. First of all: electricity is never free to produce. Running a powerplant costs the same no matter what price the electricity is at. The price goes to zero when supply greatly overceeds demand. That means I'm not paying to the electric company for the electricity but I'm still paying for the company that maintains the grid to deliver that electricity to me. It doesn't just magically hop from the powerplant to my house.