First of all, it's fun to play with this, even when there is no significant benefit.
Second, there are significant differences sometimes. The hourly price depends on supply and demand - factory consumption, weather (wind/water), power plant maintenance, etc.
Although usually "day expensive, night cheap" is good enough, there are peaks. Sometimes during the daytime, the price can be negative, or it can be 60 cents/kWh. At those times you might want to avoid using sauna for example.
You can see the prices here: https://www.nordpoolgroup.com/en/Market-data1/Dayahead/Area-Prices/ALL1/Hourly/?view=chart
Personally, my subscription is a hybrid. It's a fixed fee ± difference of the current price to the rolling average. So I actually calculate the average to the current price with a tolerance of ± 5 cents. In the chart below you can see the red line, which is the trigger for the red light (11.16). Green would trigger at 1.16. The yellow line at the bottom is the average, at 6.16.
Tomorrow afternoon the energy peaks near 100 cent/kWh because of a broken nuclear plant.
https://preview.redd.it/zjalxr3vgk1c1.png?width=502&format=png&auto=webp&s=a319efb3d0e3fc8963b930c9592151548c36e6c9