Anyone knows what's the reaction time and hysteresis? How many seconds it takes for the control to turn off when provided with low/high intensity light? How many seconds it takes for the control to turn on when a light source is removed? Does it turn OFF faster than ON or the other way round?
OR is the reaction instant?

I know, a lot of questions

When some flashes from the traffic might reach the photocell, or when low clouds are moving over the sky - it generates a kind of "noise" around the wanted threshold, so arround dusk or dawn, the threshold might be crossed multiple times. Even a weak light spill from the lamp might cause a "feedback", so it might cycle.

Response:
The CdS sensor itself respond quicker from Dark -> Light, in the range of few tens of ms max.
In the reverse, it might be up to one second. But both depend on the level - darker the threshold, or moving from brighter state, slower the response.
The rest is some filtering programmed and/or inherited in the photocell design - like the thermal inertia of the heated bi-metal concept.

The hysteresis mean, then you need a higher light level to switch OFF then to switch ON. The difference is actually called the hysteresis. It is there, either "programmed" (in the elctronic) or inherited (momentary snap-switch in the heated bi-metal has a mechanical hysteresis, what translates back to light levels).
Both (or either one alone) are there to avoid glitches when turning ON/OFF (multiple switching, before it really decides to keep it ON for the night and vice versa) due to the "noise" described above - the hysteresis is larger in amplitude, the response filter is slower, then dusk/dawn light level transitions.

Thanks.
I would like to know, is there any kind of "inertia" (represented by a capacitor in electronic designs) in the photocontrol? I mean, you don't want them to turn off in a few tens of ms, e.g. when a lightning flashes or when someone shines a flashlight on it.

Thanks.
I would like to know, is there any kind of "inertia" (represented by a capacitor in electronic designs) in the photocontrol? I mean, you don't want them to turn off in a few tens of ms, e.g. when a lightning flashes or when someone shines a flashlight on it.

If it's the thermomechanical concept (a resistor connected in series with the CdS cell heat a bi-metal strip, this control the mechanical switch), there the inertia is the thermal mass of the bimetal - it has to cool-down at dusk and heat-up at down and both takes time. So short flashes are not able to heat it to high enough temperature to shut OFF the lamp.

Cheapest electronic do not have any delay, those more expensive use or a capacitor, or the most recent use some kind of SW filtering in the embedded microcontroller - today it is not much more expensive then higher quality capacitor, but is totally insensitive to e.g. moisture.

In both cases the exact timing depend on the design, each manufacturer and/or photocell type might behave in different way. The thermomechanical design would even differ piece-by-piece, as well as with the "mood" (depend on temperature, humidity, age, cycles,...)