The power consumption (over time) will scale with the heat you ask from it. 8 amps is the current draw MAX, if you turn the dial all the way up and put the hot plate in a cold ambient environment then it will draw a steady 1000 watts. The power curve isn’t linear but say you want only 250c , then over time the power draw would be more like 4 amps/hour or 500 watts/hour.
There’s 2 ways generally power is controlled, current limiting or pulse width modulation. Current limiting would mean the heater is always on but the current to the element is controlled to limit the wattage. The Corning device you linked is micro processor controlled so there’s a good chance it’s PWM. PWM in short will send pulses of full current, full voltage (1000 watts) but it will not be a constant draw. It will ‘flicker’ as needed. This is more efficient than limiting current.
So probably it does draw 1000 watts but say the pulses are off half the time then you’re only using 500watts/hour.
So both hotplates use their maximum power draw until the temp is reached.
I tested 250c then I tested the max temp. Power draw did exact same thing Room was 60F
Thermo Scientific Cimarec 7X7" - 8.9A 1000W
Start - 8.66A
~5 min - 0A
then 8.66A every 10 seconds or so
Heidolph Hei-Tec 5.7x5.7" - 5.7A 685W
Start - 5.7A
~5 min - 0A
then 5.4A every 10 seconds or so
A note too for the larger hot plates, the heating element is not the entire top so the edges really don’t heat up as well as the center. Looking at it with a FLIR really shows how shitty and uneven they can be but even visually you can see the “burn in” after some use